Movant, Lonzo Stewart, appeals from the denial of his Rule 29.15 motion without an evidentiary hearing. We reverse and remand.
Movant was convicted, after a jury trial, of murder in the second degree and sentenced to imprisonment for 20 years. That conviction was affirmed on direct appeal. State v. Stewart, 752 S.W.2d 359 (Mo.App.1988). At trial, a State’s witness testified that movant shot the victim once and, after the victim fell, movant fired five more shots into his head. Movant admitted the shooting but testified that he acted in self-defense.
Movant’s brother, Marvin, testified on behalf of his brother. The essence of Marvin’s testimony on direct examination was that he was present at the shooting and that movant acted in self-defense. On cross-examination, Marvin was asked whether he had told Detective Poelling that he was at a party and not present at the shooting. Marvin denied making the statement. The State then called Poelling in rebuttal. He testified that when he spoke to Marvin, he and Marvin were the only ones present. Poelling testified that when he asked Marvin whether he had been present at the shooting, Marvin replied that he was not there but had been at a party.
Movant alleges the motion court erred in denying movant’s Rule 29.15 motion with*887out an evidentiary hearing because his motion contained facts not refuted by the record which could entitle movant to relief. In his motion, movant claims that he instructed trial counsel to call movant’s sister, Laura, as a surrebuttal witness. He claims he told his trial attorney that Laura would rebut Officer Poelling’s testimony by testifying that she was present when Poelling questioned Marvin and that Marvin did not tell Poelling that he was at a party at the time of the shooting. Movant contends Laura’s testimony would have helped rehabilitate Marvin’s credibility as a defense witness, after Poelling’s alleged false testimony. Movant therefore claims he was denied effective assistance of counsel.
Movant requested an evidentiary hearing. He stated in his amended Rule 29.15 motion that, in addition to his own testimony, he intended to call his trial attorney and Laura Stewart as witnesses. In denying the motion, the court ruled that whoever was present with Marvin at the time Poell-ing questioned him was a collateral issue “in that Marvin Stewart stated [to] whoever was present that he was not with his brother nor did he know what his brother had done on November 15, 1986, the date of the alleged murder. Counsel is not required to pursue collateral issues which do not support any defense.”
Whether Laura was present at Poelling’s interrogation may indeed be a collateral issue, as the motion court found. Laura’s statement that she was present, however, was not her only purported testimony. According to movant, she would have also stated that Poelling falsely testified that Marvin told him that he was not with mov-ant at the time of the shooting.
Subject to certain limited exceptions, see Williams v. State, 744 S.W.2d 814, 817 (Mo.App.1987), the motion court is required to issue findings of fact and conclusions of law on all of the issues presented. See Feemster v. State, 709 S.W.2d 172, 173 (Mo.App.1986); Rule 29.15(i). The requirements of Rule 29.15(i) are not a mere formality. Those findings and conclusions must be made with sufficient specificity to allow for meaningful review on appeal. Moore v. State, 736 S.W.2d 593, 594 (Mo.App.1987).
The motion court’s findings failed to fully address movant’s contention. In particular, the court failed to address movant’s allegation that Laura would have testified on surrebuttal that Marvin never told Poell-ing that he was not with movant at the time of the shooting. The court’s ruling does not reveal whether the court even considered this allegation. See Id.
In O’Neal v. State, 766 S.W.2d 91 (Mo. banc 1989), the Missouri Supreme Court reiterated the rules relating to appellate review of post-conviction proceedings announced in Sanders v. State, 738 S.W.2d 856 (Mo. banc 1987). Quoting Sanders, the Court said:
The Sixth Amendment guarantees the right to effective assistance of counsel. And, while this allegation is commonly found in proceedings attacking both guilty pleas and trial convictions, a mov-ant is faced with what has often been called a ‘heavy burden.’ Jones v. State, 598 S.W.2d 595, 597 (Mo.App.1980). Not only must the movant prove his allegation by a preponderance of the evidence, but the ‘heavier burden’ arises from a presumption that counsel is competent. See Strickland v. Washington, 466 U.S. 668, 689 [104 S.Ct. 2052, 2065, 80 L.Ed.2d 674] (1984); Seales v. State, 580 S.W.2d 733, 735 (Mo. banc 1979). In determining the issue of ineffective assistance of counsel, the trial court is free to believe or disbelieve evidence — contradicted or undisputed. See Jones, 598 S.W.2d at 597. And, appellate review of the trial court’s decision in ruling a Rule 27.26 proceeding is expressly ‘limited to a determination of whether the findings, conclusions, and judgment of the trial court are clearly erroneous.’ (Emphasis added). Rule 27.26(j); Futrell v. State, 667 S.W.2d 404, 405 (Mo. banc 1984). Such findings and conclusions are deemed clearly erroneous only if, after a review of the entire record, the appellate court is left with the ‘definite and firm impression that a mistake has been made.’ *888Stokes v. State, 688 S.W.2d 19, 21 (Mo.App.1985).
In order to prevail on a claim of ineffective assistance of counsel, a criminal defendant must show (1) that his attorney failed to exercise the customary skill and diligence that a reasonably competent attorney would perform under similar circumstances, and (2) that he was thereby prejudiced. Strickland, 466 U.S. at 687 [104 S.Ct. at 2064]; Seales, 580 S.W.2d at 736. A criminal defendant must satisfy both the performance prong and the prejudice prong to prevail on an ineffective assistance of counsel claim. In reviewing such a claim, courts are not required to consider both prongs; if a defendant fails to satisfy one prong, the court need not consider the other. And, a court need not determine the performance component before examining for prejudice. If it is easier to dispose of the claim on the ground of lack of sufficient prejudice, the reviewing court is free to do so. Strickland, 466 U.S. at 697 [104 S.Ct. at 2069] (emphasis added).
Courts should strive to ensure that ineffectiveness claims not become so burdensome to defense counsel that the entire criminal justice system suffers as a result.
Unlike Sanders and O’Neal, there was no evidentiary hearing in this case. Further, the findings of the motion court are clearly erroneous because they failed to address movant’s contention. The record on appeal does not refute movant’s allegation. The alleged testimony of Laura, considered in a light most favorable to movant, could have the reasonable probability of rehabilitating Marvin’s credibility. Clearly, Marvin’s credibility was material to mov-ant’s self-defense theory at trial. See State v. Holly, 697 S.W.2d 250, 253 (Mo.App.1985). Issues such as the credibility of the witnesses who might testify at the motion hearing, trial strategy, and the determination of lack of prejudice cannot conclusively be resolved against movant based only upon the motion and the files and records of this case. See Rule 29.15(g).
The judgment of the trial court is reversed and this case is remanded with directions to the motion court to grant an evidentiary hearing. In view of our holding, we do not address movant’s remaining point relating to procedural deficiencies in the motion court.
CRIST, J., concurs in result only. REINHARD, J., dissents in separate opinion.