Recently, Bart Ehrman was making the media circuit talk about his new book, Jesus, Interrupted: Revealing the Hidden Contradictions in the Bible (And Why We Don’t Know About Them). Another of his alleged discrepancies in the Bible is that “in Mark’s Gospel Jesus tells Peter that he will deny him ‘three times before the cock crows twice.’ In Matthew’s gospels he tells him it will be ‘before the cock crows.’ Well which is it–––before the cock crows once or twice?” 
In response let me first point out that—as his more attentive students have likely discovered—Professor Ehrman is engaged in a cocky game of slight-of-mind. The truth is that Matthew does not tell us how many times the rooster crowed, he simply tells us that the rooster crowed (Mt. 26:34). As such Ehrman is only knocking down a straw man.
Furthermore, only an extreme literalist bent on undermining Scripture would attempt to make this particular passage walk on all fours. In recounting past events or stories, we obviously don’t all highlight the same details. In the case at hand, Mark simply provides a bit more detail than does Matthew (Mt.26:34; Mk 14:30).
Finally, Ehrman has set up a rigged game in which it’s impossible for him to lose. Since Matthew and Mark do not provide identical testimonies he cries contradiction. Conversely, if they had provided identical testimony he would charge them with collusion.
In sharp contrast to Ehrman’s methodology, credible scholarship looks for a reliable core set of facts in order to validate a historical account. In this case, Matthew and Mark merely provided complementary perspectives.
So there’s no problem and we don’t have to make a big deal out of Bart Ehrman’s all too convenient cock crowing conundrum. It’s easily explained, it’s not a problem and certainly isn’t a reason for us to say that the Bible can’t be trusted. In fact, the reasons the Bible can be trusted are overwhelming including the evidence for the manuscripts themselves, archaeological evidence, predictive prophecy and scriptural synergy. All this is available in various sources, especially in my new resource Memorable Keys to Essential Christian D-O-C-T-R-I-N-E. It’s available at our Website at www.equip.org or by calling us at 1-888-700-0274.
 Bart D. Ehrman, Jesus, Interrupted: Revealing the Hidden Contradictions in the Bible (And Why We Don’t Know About Them) (New York, Harper One, 2009), 7.