If you asked most people how many times Peter denied Jesus, you would overwhelmingly get the answer of three. It seems pretty straight forward. You might be surprised then to discover that many people actually believe that Peter denied Jesus six times! How do they get that? When you look at the account of the denial of Jesus in each of the Gospels, there is variation in the detail. When did the cock crow? Where was Peter? Who was the person he was speaking to? What did Peter say? The only way to harmonize these accounts is to suggest that Peter denied Jesus six times and that certain Gospels only record three of the six. An example can be found in this blog post.
For many people this is a serious issue. For myself, it is no issue at all. The Gospels agree that Peter denied Jesus three times. The variations suggest that there were a number of traditions about this event, which strengthens the case for its historicity. Differences in detail do not trouble me at all.
But there is something that does trouble me. In the Gospels, Jesus specifically prophesies that Peter will deny him three times (Matt 26:34, Mark 14:30, Luke 22:34). And yet some people are so intent on harmonizing the passages that they are willing to turn Jesus into a false prophet. This tells me that some people see the authority of the Bible as trumping the authority of Jesus. I am not denying the inspiration of the Bible (I very much affirm inspiration), but I have much more loyalty to Jesus. Jesus prophesied and the prophecy came true. That is of primary importance. Any differences in the description of that fulfillment are only secondary. I love the Bible, but I love the Bible for what it tells me about Jesus. We must always give first place to Jesus and not try to raise the authority of the Bible above him.
If you are interested in learning more about how to work through these passages, you might be interested in Edwin Chong’s article in the Quodlibet Journal.