dissenting:
This dispute between the Bronx Household of Faith, a Christian church, and the New York City Board of Education is old and bitter. Bronx Household wishes to use school facilities for Sunday worship services; the Board wishes to keep them out and invokes a rule .precluding groups who meet on school premises after hours from “holding religious worship services, or otherwise using a school as a house of worship.” Standard Operating Procedures Manual § 5.11 (“SOP § 5.11”).1
While I agree with Judge Calabresi that this dispute is ripe for adjudication, and join his opinion in that limited respect without reservation,2 I cannot agree that SOP § 5.11 is viewpoint neutral. Indeed, after comparing the purposes of Bronx Household’s proposed use of school prop*124erty with the purposes for which the Board has opened that property to the public, I can only conclude that by promulgating SOP § 5.11 the Board has engaged in a form of invidious viewpoint discrimination forbidden by the First Amendment. With the history of this dispute in mind and in light of the Supreme Court’s recent decision in Good News Club v. Milford Central School, 533 U.S. 98, 121 S.Ct. 2093, 150 L.Ed.2d 151 (2001), I vote to affirm the district court’s permanent injunction.
Rather than inquiring into the purposes of the proposed expressive activity and the purposes of the forum, Judge Calabresi follows a different analytical course, with which I cannot agree. Starting with the premise that in a “limited public forum” the government may restrict any expressive activity that does not “parallel” expressive activity the government has already chosen to permit, Judge Calabresi asks whether “worship [is] merely the religious analogue of ceremonies, rituals, and instruction [which the Board has chosen to permit], or ... [whether it is] a unique category of protected expression.” Cala-bresi Op., supra at 92. He then completes the syllogism by holding that worship is sui generis, unlike expressive activity the Board has already chosen to permit, and thus impermissible. The result is Bronx Household’s excommunication from the broad group of after-school users who are welcome on school property.
Judge Calabresi’s approach is fatally defective in two principal ways: (1) He fails to define the “limits” of the Board’s limited public forum, rendering the comparison he draws between permitted expressive activity and Bronx Household’s proposed expressive activity so indeterminate and malleable that its result is foreordained; and (2) He fails to articulate an objective definition of “worship,” the term he uses to describe Bronx Household’s proposed expressive activity, choosing instead to leave that task to the Board and thereby likely ensuring that the Board’s entanglement in the process will violate the Establishment Clause.
The First Amendment is not like a book in the “Choose Your Own Adventure” series, in which it is easy—albeit theoretically improper—to select an outcome and, working backwards, decide how the plot and characters will develop; nor, for that matter, may we decline the adventure itself. The First Amendment does not teach Judge Calabresi’s simple calculus. Cf. Int’l Soc’y for Krishna Consciousness, Inc. v. Lee, 505 U.S. 672, 693-94, 112 S.Ct. 2701, 120 L.Ed.2d 541 (1992) (Kennedy, J., concurring) (“Our public forum doctrine ought not to be a jurisprudence of categories rather than ideas.... ”). Because I agree with Judge Calabresi that we must decide this case, because I conclude that the Board has engaged in impermissible viewpoint discrimination, and because Judge Calabresi’s approach relies more on judicial legerdemain than judicial reasoning, I must respectfully dissent from the *125court’s decision to vacate the permanent injunction.
I. Bronx Household’s Free Speech Claim
A. The Board’s Viewpoint Discrimination
Despite the two flaws in Judge Calabre-si’s approach, I begin with three points on which he and I are in agreement. I agree that in a limited public forum, the government may exclude all entities except those “entities of similar character” to those it has chosen to include, Perry Educ. Ass’n v. Perry Local Educators’ Ass’n, 460 U.S. 37, 48, 103 S.Ct. 948, 74 L.Ed.2d 794 (1983), as long as any such exclusion is not a facade for covert viewpoint discrimination, Cornelius v. NAACP Legal Def. and Educ. Fund, Inc., 473 U.S. 788, 812, 105 S.Ct. 3439, 87 L.Ed.2d 567 (1985). Indeed, we have concluded, a limited public forum is (1) a sub-set of the designated public forum as to “expressive activities of [the] genre” the government has chosen to permit on its property, Travis v. Owego-Apa-lachin Sch. Dist., 927 F.2d 688, 692 (2d Cir.1991), and (2) a sub-set- of the nonpublic forum as to all other expressive activities. See also Arkansas Educ. Television Comm’n v. Forbes, 523 U.S. 666, 677, 118 S.Ct. 1633, 140 L.Ed.2d 875 (1998) (holding that if the government excludes “a speaker who falls within the class to which a designated public forum is made generally available” its decision is subject to strict scrutiny). I also agree that we must be careful not to articulate a standard that would simply require that “any public school opened for civic meetings, [be] open[ ] for use as a church, synagogue, or mosque.” Good News Club, 533 U.S. at 139, 121 S.Ct. 2093 (Souter, J., dissenting). And, finally, I agree that courts should not analyze the “substance” of proposed expressive activity as the district court did in this case. See Bronx Household of Faith v. Bd. of Educ. (Bronx Household III), 400 F.Supp.2d 581, 591 (S.D.N.Y.2005) (describing Bronx Household’s proposed, activity as “singing songs and hymns; teaching from the Bible.”). By deconstructing religious worship into components, the district court denigrates it.3
Judge Calabresi and I part ways, however, in how we propose to ascertain whether the Board is just excluding an entity dissimilar to those it has already chosen to permit on its premises or whether it is engaging in unlawful viewpoint discrimination. I would compare the. purposes of Bronx Household’s proposed expressive activity to the purposes for which the Board has created its limited public forum and, if the fit is close, inquire searchingly of the government’s motives. This accords with the various cases Judge Calabresi cites in his opinion, but barely analyzes. The Good News Club Court, for instance, emphasized purpose. Compare Good News Club, 533 U.S. at 108, 121 S.Ct. 2093 (“Milford has opened its limited public forum to activities that serve a variety of purposes ....”) (emphasis added), and id. (“[T]here is no question that teaching morals and character development to children *126is a permissible purpose under Milford’s policy .... ”), and id. at 109, 121 S.Ct. 2093 (discussing “the [Lamb’s Chapel] films’ purpose”), with id. at 131, 121 S.Ct. 2093 (Stevens, J., dissenting) (distinguishing discussion of “political issues from meetings whose principal purpose is to recruit new members to join a political organization”) (emphasis added).4 And our court has often deemed analysis of the parties’ purposes essential to resolution of limited public forum cases. See Deeper Life Christian Fellowship, Inc. v. Bd. of Educ., 852 F.2d 676, 680 (2d Cir.1988) (government’s purpose relevant to determining whether property is public forum or nonpublic forum); Knolls Action Project v. Knolls Atomic Power Lab., 771 F.2d 46, 50(2d Cir.1985) (ostensible subject-matter restriction “impermissible [if] it was motivated [in fact] by a dislike of the content of [plaintiff]’s message”).
More importantly, whether Bronx Household’s proposed expressive activity constitutes “worship” can only be discerned by inquiring of that activity’s purpose. See Welsh v. United States, 398 U.S. 333, 339, 90 S.Ct. 1792, 26 L.Ed.2d 308 (1970) (accepting the subjectivity of “religious belief’ and abjuring any objective definition of the term); United States v. Seeger, 380 U.S. 163, 85 S.Ct. 850, 13 L.Ed.2d 733 (1965) (same); cf. Murdock, 319 U.S. at 109, 63 S.Ct. 870 (noting evangelical purpose to sale of religious literature).
Under the approach most faithful to Supreme Court precedent, whether Pastor Hall chooses to label Bronx Household’s proposed expressive activity a “worship service” is not determinative; we must independently examine the purpose of that activity. Compare McCreary County v. ACLU, 545 U.S. 844, 125 S.Ct. 2722, 2732, 162 L.Ed.2d 729 (2005) (discerning hidden religious purpose) with N. Pac. Union Conference Ass’n of the Seventh-Day Adventists v. Clark County, 118 Wash.App. 22, 28-29, 74 P.3d 140 (2003) (discussing whether “education” should be considered “ ‘a vital part of the Church’s worship program’” for tax purposes). Defendants’ purpose in opening school property to the public is to improve “school-community relations in ways that can enhance community support for the school.” Cahill Decl. ¶ 14; Farina Decl. at ¶ 9 (noting that the Board wishes to “expand enrichment opportunities for children and to enhance community support for the schools”) (emphasis added). Simply put, defendants wish to foster a community in their geographic vicinity in ways that will inure to their benefit. Upon review of the record, Bronx Household’s proposed expressive activity fits within this paradigm. Bronx Household’s essential purpose is the development of a community of believers, which has as its anticipated result increased community support for the school. See 1st Hall Dep. at 19, 20, 38, 46.
Because the fit between the government’s purpose in opening the forum and the purpose of Bronx Household’s proposed expressive activity is sufficiently close, more searching scrutiny of the government’s motives is required. Cf. Peck ex rel. Peck v. Baldwinsville Cent. Sch. Dist., 426 F.3d 617, 631 (2d Cir.2005) (Calabresi, J.) (postulating hostility to religion from teacher’s conduct). The Board’s avowed purpose in enforcing the regulation in this case, see Bronx Household III, 400 *127F.Supp.2d at 599 (noting that “[t]he Board is quite candid in acknowledging its intent to ‘reinstitute a policy that would prevent any congregation from using a public school for its worship services’ ”), and its long-standing hostility to religious groups, leads ineluctably to the conclusion that the Board, in fact, has undertaken to exclude a particular viewpoint from its property.
I acknowledge Judge Calabresi’s concern that New York’s schools not resemble St. Patrick’s Cathedral. However, analysis of the parties’ purposes does not raise that concern; it leaves the Board ample room to regulate the use of its property.5 As the Supreme Court explained in Good News Club, the government “may be justified ‘in reserving [a forum] for certain groups.’ ” 533 U.S. at 106, 121 S.Ct. 2093 (emphasis added); Perry, 460 U.S. at 49, 103 S.Ct. 948(“We believe it is more accurate to characterize the access policy as based on the status of the respective unions ....”) (emphasis added). The Board thus remains free to distinguish between outside speakers and student-sponsored groups (as indeed the text of SOP § 5.11 hints it may). Cf. Bronx Household III, 400 F.Supp.2d at 600 n. 18 (noting that the Board could “amend the SOPs to create a neutral distinction based on the speaker”). Moreover, the Board may also impose reasonable time, place or manner restrictions on Bronx Household.
B. Two Flaws in Judge Calabresi’s Reasoning
Judge Calabresi’s conclusion that “defendants’ exclusion of worship services is viewpoint neutral,” Calabresi Op., supra at 106, is grounded not upon a comparison of the purposes of the activities allowed and the purpose of Bronx Household’s proposed activity, but upon a comparison between the expression already permitted on school premises and “worship.” Compare Calabresi Op., supra at 103 (comparing worship services to “Boy Scouts rituals or ... Elks Club ceremonies” and finding substantial differences) with Good News Club, 533 U.S. at 111, 121 S.Ct. 2093 (finding few differences between Good News Club’s proposed activity and Boy Scouts rituals). After he pronounces worship sui geneñs, Judge Calabresi not surprisingly finds that “worship” is not included within the set of expressive activity hitherto permitted by the Board. This will not do. In order to determine whether an element is within a set, a court should both define the set, see Child Evangelism Fellowship of New Jersey Inc. v. Stafford Township Sch. Dist., 386 F.3d 514, 527 (3d Cir.2004) (discussing the limited public forum’s limits), and analyze the element, to discern whether it has the attributes required for admission to the set, see Goulart v. Meadows, 345 F.3d 239, 252 (4th Cir.2003) (explaining the importance of identifying “which of ... various indicia of similarity is the relevant one”). See generally Nix v. Hedden, 149 U.S. 304, 13 S.Ct. 881, 37 L.Ed. 745 (1893) (determining whether tomatoes should be classified as “fruit” or “vegetable” by first defining “fruit” and “vegetable” and then analyzing “tomatoes”). Yet Judge Calabresi defines neither the set— the “limits” of the limited public forum— nor the element—“worship.” His comparison is therefore susceptible to reductio ad absurdum, as both the scope of the set and the nature of its prospective member remain substantially unknown.6
*128(1) Judge Calabresi does not define the limits of the limited public forum.
The first flaw in Judge Calabresi’s analysis lies with his delimitation of the limited public forum. He says that we are bound by our decision in Bronx Household of Faith v. Community School District No. 10 (Bronx Household I), 127 F.3d 207, 211-14 (2d Cir.1997), that the school has created a limited public forum. But the character of a forum is defined by its uses and the uses to which it is put change over time. See Paulsen v. County of Nassau, 925 F.2d 65, 69 (2d Cir.1991); cf. Grayned v. City of Rockford, 408 U.S. 104, 116, 92 S.Ct. 2294, 33 L.Ed.2d 222 (1972) (stating that “[t]he crucial question is whether the manner of expression [that the petitioner wishes to engage in] is basically incompatible with the normal activity of a particular place at a particular time”) (emphasis added). Therefore, while his implicit assumption that the character of the forum has not changed may be correct, he cannot reach this conclusion by simple judicial say-so; such a conclusion must be based on a factual inquiry into the forum’s current uses, not those of a decade ago.
Even were I to agree with Judge Cala-bresi that we should unquestioningly adopt our decade-old legal analysis of the forum, the term “limited public forum” does no judicial work unless we know “the class to which ... [the] forum is made generally available,” Forbes, 523 U.S. at 677, 118 S.Ct. 1633. And on this point his I opinion is silent.7
*129(2) Judge Calabresi does not define worship.
Judge Calabresi’s reasoning has a second flaw: It posits that' judges can define “worship.” He assumes that worship is distinguishable from activities that are plainly within the forum’s limits: These include gathering for the purpose of gaining religious instruction, engaging in Bible study, and, if it be the disposition of the participant in such activities, feeling the deity’s presence. Indeed, to some men and women of faith, political activism, proselytizing, or even education,8 amount to worship.9 How can one quarrel with Justice Souter’s classification of Good News Club’s after-school Bible study program, permitted by the Court, as “worship,” 533 U.S. at 138, 121 S.Ct. 2093 (Souter, J., dissenting)? Of course, because the concept of worship is so ephemeral and inherently subjective, Judge Cala-bresi is able to indulge his preference that worship be defined not by what it is, but by what it is not. And what worship is not, in his view (and convenient for his purposes), is anything that the Board has already permitted to occur in the forum. Yet the fact is that none of us, who are judges, are competent to offer a legal definition of religious worship.10
Even assuming that judges could define “worship,” Judge Calabresi does not explain how he would do so—perhaps he knows it when he sees it?11 Cf. Jacobellis v. Ohio, 378 U.S. 184, 197, 84 S.Ct. 1676, 12 L.Ed.2d 793 (1964) (Stewart, J., concurring). Judge Calabresi suggests that one may worship “mammon, sex, or art.” Calabresi Op., supra at 104. Perhaps he means to concede that the term can con*130note simple reverence for something or someone (like “Tiger Woods” or, in earlier eras, “Frank Sinatra,” “Rita Hayworth,” or “The Beatles”). See Webster’s Third International Dictionary 2637 (1981) (defining worship as “to regard with respect, honor, or devotion”). Or perhaps he means something different; but if so, there is no hint to art history professors everywhere as to how they might turn their classrooms into houses of worship—surely a useful feat! In short, Judge Calabresi speaks with an obliquity of which any prophet would be proud.
Judge Calabresi’s various attempts to avoid defining “worship” are unavailing.12 First, Judge Calabresi suggests that “Good News Club itself recognized this subject matter, worship, as falling outside the boundary of its viewpoint discrimination jurisprudence.” Calabresi Op., supra at 101. Good News Club did nothing of the sort. The Court simply declined to reach the question presented by this case, which, while not necessary to that case, is to this one, see Good News Club, 533 U.S. at 112 n. 4, 121 S.Ct. 2093 (“[W]e conclude that the Club’s activities do not constitute mere religious worship, divorced from any teaching of moral values.”), as Judge Cala-bresi recognizes elsewhere in his opinion, when it suits him, see Calabresi Op., supra at 94 (noting that “the instant appeal’s central question” was “unresolved”).
Second, Judge Calabresi relies heavily on Pastor Robert Hall’s admission that Bronx Household wishes to conduct worship services on school premises. But if we accept plaintiffs’ self-description, we should accept their self-definition. And Pastor Hall defines worship as the ascription of “worth to a variety of values and skills,” 1st Hall Dep. at 41-42 (discussing “worshiping” a sunset or work of art); Bronx Household of Faith v. Bd. of Educ. (Bronx Household II), 226 F.Supp.2d 401, 424 (S.D.N.Y.2002), not much different in kind from the dictionary definition, supra, “to regard with respect, honor, or devotion.” If that is to be the operative definition of “worship,” Bronx Household is surely correct that the Board permits other community groups that “ascribe worth to a value or skill”—i.e., “worship”—to use their facilities. Cf. id. (“[T]he Semanonans Stickball players ... would likely join plaintiffs in worshiping David Wells’ pitching prowess.”).13
Moreover, and more fundamentally, Judge Calabresi, while he dismisses Bronx Household’s as applied challenge to SOP § 5.11, does not reckon with its facial challenge to the rule. Compl. at 6; cf. Faith Ctr. Church Evangelistic Ministries v. Glover, 462 F.3d 1194, 1219 (9th Cir.2006) (Tallman, J., dissenting) (“Faith Center also brought a facial challenge to the policy.”). Bronx Household’s facial challenge to SOP § 5.11 implicates the rights of other religious groups, which might not “make [the] nice admission” that they wish to engage in “worship.” Id.
*131Finally, any attempt to define worship places Judge Calabresi upon the horns of a dilemma. Either he clarifies the meaning of “worship,” and risks entangling the judiciary in religious controversy in violation of the First Amendment, or he delegates the task of flouting the Establishment Clause to the Board, which will no doubt have to “interpret religious doctrine or defer to the interpretations of religious officials” in order to keep worship, and worship alone, out of its schools. Commack Self-Service Kosher Meats v. Weiss, 294 F.3d 415, 427 (2d Cir.2002); see also Glover, 462 F.3d at 1220 (Tallman, J., dissenting); cf. Good News Club, 533 U.S. at 127, 121 S.Ct. 2093 (Scalia, J., concurring).
II. The Board’s Establishment Clause Defense
Judge Calabresi does not consider whether the Board can show a compelling interest in applying SOP § 5.11 to Bronx Household; because, however, I would find that the Board’s exclusion of Bronx Household from the forum is viewpoint-discriminatory, I must address the argument, advanced in the district court, that the Board can justify its position as necessary to avoid an Establishment Clause violation. While avoiding an Establishment Clause violation may as a general matter be a compelling state interest, in this case, the Board’s argument is unavailing because Bronx Household’s worship at the school does not offend the Establishment Clause.
The endorsement test—which the Supreme Court now uses to identify Establishment Clause violations—asks whether “an objective observer, acquainted with the text, legislative history, and implementation of the [challenged law or policy], would perceive it as a state endorsement” of religion. Santa Fe Indep. Sch. Dist. v. Doe, 530 U.S. 290, 308, 120 S.Ct. 2266, 147 L.Ed.2d 295 (2000). The Board argues— and Judge Calabresi obliquely suggests— that permitting Bronx Household the use of school property on Sundays amounts to government endorsement of religion in two ways: (1) It suggests that the state favors religion over non-religion; and (2) Because Bronx Household uses school premises on a more frequent basis than other religious groups, it suggests that the state favors Christianity over Judaism, Islam, or other faiths. Neither argument has merit.
As we recognized in Deeper Life, “ ‘the semblance of official support is less evident where a school building is used at night ... by religious organizations, under a program that grants access to all charitable groups.’ ” 852 F.2d at 681 (citing Brandon v. Bd. of Educ., 635 F.2d 971, 978-79 (2d Cir.1980)); see also Lamb’s Chapel, 508 U.S. at 395, 113 S.Ct. 2141(noting that meetings were not “during school hours ... [or] sponsored by the school ... [and are] open to the public, not just church members”). Just so, Bronx Household does not meet during school hours, and its meetings are open to all. See 1st Hall Dep. at 30 (“Our services are always open to the public.”).14 Nor do religious groups dominate the forum. See Bronx Household III, 400 Supp.2d at 596; cf. Widmar, 454 U.S. at 275, 102 S.Ct. 269. Under these circumstances, there is no likelihood that “an adult who, taking full account of the policy’s text, history, and implementa*132tion, do[ing] so mindful ... [of the particular perspective of] impressionable schoolchildren,” Skoros, 437 F.3d at 23, would understand Bronx Household’s use of school premises to reflect the government’s preference for religion over non-religion.15
I also disagree that the reasonable observer is likely to believe the government favors Christianity over other faiths because, due to the vagaries of the school calendar, the forum is available on Sundays—when Christians worship—and not on Saturdays or Fridays—which are holy to Jews and Muslims. As the Supreme Court explained in Zelman v. Simmons-Harris, 536 U.S. 639, 122 S.Ct. 2460, 153 L.Ed.2d 604 (2002), and Good News Club, an Establishment Clause violation does not result from either private choice or happenstance. Zelman, 536 U.S. at 652, 122 S.Ct. 2460; Good News Club 533 U.S. at 119 n. 9, 121 S.Ct. 2093; see also Harris v. McRae, 448 U.S. 297, 319, 100 S.Ct. 2671, 65 L.Ed.2d 784 (1980) (“[I]t does not follow that a statute violates the Establishment Clause because it happens to coincide or harmonize with the tenets of some or all religions.”) (internal quotation marks omitted).
To the extent the Board is troubled by Bronx Household’s use of its property, it is free to impose different reasonable time, place or manner restrictions. Ward v. Rock Against Racism, 491 U.S. 781, 790, 109 S.Ct. 2746, 105 L.Ed.2d 661 (1989).
Ht H* Hi * ^ *
In the end, this case is one that requires judges to draw lines. Judge Leval has drawn a prudential line in the sand and declines to cross it to decide this case. Judge Calabresi, meanwhile, has drawn a circle around our schools to keep worship (whatever that may be) out. Cf. Mozert v. Hawkins County Bd. of Educ., 827 F.2d 1058, 1073 (Boggs, J., concurring) (“He drew a circle that shut me out—Heretic, Rebel, a thing to flout. But Love and I had the wit to win / We drew a circle that took him in!”). The approach I follow, while admittedly imperfect in this uncertain legal terrain, at least abjures sleight of hand and ipse dixits. It is also more sensitive to Bronx Household’s First Amendment rights. Yet there is no doubt that this particular dispute—no stranger to the Supx'eme Court and now focused on worship—would benefit from a more conclusive resolution by that Court.
. What is .termed "Revised” SOP § 5.11 in the court’s per curiam opinion, I call simply SOP§ 5.11.
. I agree with Judge Leval that we should not reach out to decide unnecessary constitutional questions. The Board, however, has repeatedly and implacably sought to exclude religious viewpoints—whether out of the mistaken belief that such exclusion is necessary *124to comply with the Establishment Clause or due to some hostility to religious groups. Indeed, this marks the third time that a New York school board has denied religious groups access to school property. Under these circumstances, and in light of the fact that I believe the Board has adopted SOP § 5.11, I think we owe the litigants a duty to decide this dispute now; the alternative would permit the Board to rely on the in terrorem effect of SOP § 5.11 to prevent Bronx Household from pursuing its principal goal—the establishment of a community of believers—as Bronx Household would need to account at every turn for the possibility that at any moment it might be forced to resume its peripatetic search for a building wherein to house its worshipers. Cf. Abbott Labs. v. Gardner, 387 U.S. 136, 152, 87 S.Ct. 1507, 18 L.Ed.2d 681 (1967).
. The district court's approach is also impractical, for if worship is merely the singing of hymns and reading from the Bible, the singing of hymns might be considered simply a vibration of the vocal chords; finally, the district court’s approach seems in tension with the Supreme Court’s decision in Murdock v. Commonwealth of Pennsylvania, 319 U.S. 105, 109, 111, 63 S.Ct. 870, 87 L.Ed. 1292 (1943) ("[T]he mere fact that the religious literature is 'sold' by itinerant preachers rather than ‘donated’ does not transform evangelism into a commercial enterprise.”). I note in passing that for these same reasons I fail to see how the Board could grant Bronx Household’s putative future application in part while denying it in part. Cf. Leval Op., supra at 119.
. See also Rosenberger v. Rector & Visitors of the Univ. of Virginia, 515 U.S. 819, 829, 115 S.Ct. 2510, 132 L.Ed.2d 700 (1995); id. at 846, 115 S.Ct. 2510 (O’Connor, J., concurring) ("This insistence on government neutrality toward religion explains why we have held that schools may not discriminate against religious groups by denying them *127equal access to facilities that the schools make available to all.”).
. Moreover, because the Board has a compelling interest in avoiding Establishment Clause violations, it can exclude religious groups whose presence would convey to the public the message that the government endorses religion (or a particular religion). Cf. Lamb’s Chapel, 508 U.S. at 394-395, 113 S.Ct. 2141.
. Indeed, Judge Calabresi holds that "worship” is sui generis. But how is it possible to *128determine whether one activity that is by hypothesis in a class of its own, Webster’s Third International Dictionary 2286 (1981) (defining "sui generis"), is within a set comprised of other activities?
. I hold no illusion that defining the limits of a limited public forum is an easy task. For instance, Cornelius instructs that we should consider the government's intent. 473 U.S. at 802, 105 S.Ct. 3439; see, e.g., Deeper Life, 852 F.2d at 680; Calash v. City of Bridgeport, 788 F.2d 80, 83 (2d Cir.1986). But how to distinguish a change of mind—which the government, like any property owner, is assuredly permitted, see, e.g., Perry, 460 U.S. at 46, 103 S.Ct. 948—from viewpoint hostility? Compare Knolls, 771 F.2d at 49-50 ("In the instant case, therefore, whatever previous use has been allowed does not foreclose KAPL from asserting its rights at this time.”) (emphasis added) with Robert C. Post, Between Management and Governance: The History and Theory of the Public Forum, 34 UCLA L.Rev. 1713, 1756 ("If the reach of the forum is determined by the intent of the government, and if the exclusion of the plaintiff is the best evidence of that intent, then the plaintiff loses in every case.”), and with New York Magazine v. Metro. Transp. Auth., 136 F.3d 123, 129-30 (2d Cir.1998). On the other hand, if we fix the definition of the forum at the time the government first permits members of the public to use its property for expression, how do we account for the inherently contingent nature of a property's taxonomy? See ISKON, 505 U.S. at 698, 112 S.Ct. 2701 (Kennedy, J., concurring) (arguing that if "expressive activity would be appropriate and compatible with [a property], the property is a public forum”); see also Lebron v. Nat’l R.R. Passenger Corp., 69 F.3d 650, 655-56 (2d Cir.1995); supra (discussing Grayned).
Moreover, courts sometimes make this task even more difficult by covertly collapsing the inquiry into forum definition and forum boundary. See, e.g., Bd. of Educ. of Westside Cmty. Schs. v. Mergens, 496 U.S. 226, 246-50, 110 S.Ct. 2356, 110 L.Ed.2d 191 (1990) (inquiry into whether a secondary school had in fact opened a limited public forum within the meaning of 20 U.S.C. § 4071(a) conducted in tandem with inquiry into whether the secondary school provided "equal access”); Gregoire v. Centennial Sch. Dist., 907 F.2d 1366, 1375-76 (3d Cir.1990) (considering at the same time whether the school had in fact tightened its control over expressive activity on its premises and whether it was engaging in impermissible viewpoint discrimination).
While I believe that these tensions in First Amendment doctrine are ripe for Supreme Court clarification-in this respect, at least, I agree with Judge Leval—Judge Calabresi should not so easily eschew his obligation to define the contours of the limited public forum the Board has allegedly created.
. Cf. DeBoer v. Village of Oak Park, 267 F.3d 558, 568 (7th Cir.2001) ("In adopting the philosophical and theological position that prayer ... can never be 'civic,’ the Village has discriminated....”); Lassonde v. Pleasanton Unified Sch. Dist., 320 F.3d 979, 984 (9th Cir.2003) (suggesting that "proselytizing, no less than prayer, is [worship]”) (internal quotation marks omitted); Seventh-Day Adventists, 118 Wash.App. at 28-29, 74 P.3d 140 ("[T]he Church maintains that worship must be broadly defined to include missionary work, education, charitable giving, communication, publication, and planning and growth activities because these are 'a vital part of the Church's worship program.' ").
. Moreover, as Judge Bybee explained in his dissent from the Ninth Circuit’s denial of rehearing en banc in Faith Center Church Evangelistic Ministries v. Glover, Judge Calabresi may assume a definition of worship that works to "treat[] religious groups differently.” 480 F.3d 891, 901 (9th Cir.2007) (Bybee, J., dissenting from denial of rehearing en banc) (explaining that "PJiturgically oriented denominations such as Episcopalians and Catholics will [likely] find themselves subject to greater burdens [as] [t]he worship elements of their services are more distinct and easily severable from the non-worship elements”).
. I do not suggest that "worship” is not possible to define—just that it is impossible for a court to define. Were worship truly legally indistinguishable from activities carried on from a "religious perspective,” laws like the Equal Participation of Faith-Based Organizations, 69 Fed. Register 41,712 (July 9, 2004) (codified at 24 C.F.R. § 5.109) (prohibiting only "inherently religious activities”, and defining the term to include worship, religious instruction, or proselytism), might well be unconstitutional.
. On this score, I find Judge Calabresi’s treatment of Widmar v. Vincent singularly unpersuasive. Widmar counsels that we should decline to establish a line which, when crossed, transforms the " 'singing [of] hymns, reading scripture, and teaching biblical principles,' ... [into] unprotected ‘worship.’ ” See Widmar, 454 U.S. 263, 270 n. 5, 102 S.Ct. 269, 70 L.Ed.2d 440 (1981) (internal citation omitted). But Judge Calabresi simply dismisses Widmar with the cursory explanation that "Widmar ... did not conclude that the exclusion of worship constituted viewpoint discrimination.” Calabresi Op., supra at 104. He ignores the question actually posed, and deemed unanswerable, by the Widmar Court: What is worship?
. Nor can I agree with Judge Leval that the Board is likely to propound a useful definition of worship at some future date. I see no evidence in the record that the Board is prone to giving fulsome explanations concerning its decisions to grant or deny applications to use school facilities.
. Judge Calabresi notes that Pastor Hall distinguished worship from Boy Scouts meetings. But he quotes selectively from Pastor Hall's deposition; Pastor Hall also explicitly explains that "[w]e will ascribe worship or praise to David Wells when he almost pitched a second no-hitter.... We will praise a sunset. We will also praise a work of art. We will ascribe worth and value to something that we find valuable.” 1st Hall Dep. at 41-42. Reading Pastor Hall’s deposition "sympathetically,” I cannot but conclude that his definition of worship is broader than the (un-articulated) definition upon which Judge Cal-abresi relies.
. While it is of course true that a Muslim might not be welcome at Bronx Household’s worship service, 2d Hall Dep. at 39, it is beyond cavil that the Boy Scouts—a group the Board readily permits on school property—also exclude those who refuse to adopt their core beliefs, see Boy Scouts of America v. Dale, 530 U.S. 640, 120 S.Ct. 2446, 147 L.Ed.2d 554 (2000). Thus, I do not see how the Board could deny Bronx Household’s putative future application on this ground without also denying applications from, among others, the Boy Scouts. Cf. Leval Op., supra at 120.
. Indeed, this case seems the precise opposite of Van Orden v. Perry. In Van Orden, Justice Breyer noted that "the short (and stormy) history of the courthouse Commandments’ displays demonstrates the substantially religious objectives of those who mounted them.” Van Orden, 545 U.S. 677, 125 S.Ct. 2854, 2871, 162 L.Ed.2d 607 (2005) (Breyer, J., concurring). Here, the decade-long (and equally stormy) history of the Board's dispute with Bronx Household is compelling evidence that the Board lacks a religious objective.