Another discrepancy that Dr. Ehrman often brings up is “Which day was Jesus crucified?” This is a very complicated question that Dr. Ehrman explains in his book at length. The Synoptic Gospels – Matthew, Mark, and Luke – portray Jesus as crucified on Friday. Dr. Ehrman argues that John actually changes the day. He asserts that John wants to portray Jesus crucified not on Friday after the Passover meal, but on Thursday before the Passover meal. He claims that John wants to portray Jesus as being crucified the very moment that the Passover lambs were being slaughtered. Therefore, because the lambs were being slaughtered on Thursday, supposedly John’s Gospel wants to put Jesus’ crucifixion on Thursday as well. So Dr. Ehrman makes his case that in fact, John and the Synoptics disagree with each other.
But there are reasons to believe that Dr. Ehrman is reading too much into the text itself. He looks at the Last Supper description in John 13, and argues “Where is the description of the Passover meal? There is no description of the Passover meal. Basically it looks like a normal meal with Jesus washing his disciples’ feet.” But what Dr. Ehrman does not recognize here is that John may have had reasons for not including the full discussion of the Passover meal. He may have wanted to tell things that were left out of the Synoptic Gospels. We have every good reason to think that John knew the Synoptic Gospels. He would not have wanted to just retell the same story, once again. So apparently, John wanted to hone in on Jesus’ washing of the disciples’ feet at that meal. Just because he omits things does not mean there is a contradiction. Authors cannot say everything. By definition, all historical accounts are selective. Therefore, that John omits discussions on the meal does not form a contradiction.
Dr. Ehrman also talks about the phrase, “the day of preparation.” He argues that John is describing Jesus’ death as happening on the day of preparation of Passover when the Passover lambs were prepared for the meal. But the term “the day of preparation” is not naturally taken that way. The term “the day of preparation” is actually very much a standard term for “Friday” – the day of preparation not for the Passover meal, but for the Sabbath. In fact, John confirms this. In John 19 they wanted to take Jesus’ body down from the cross because the next day was a Sabbath day. This tells us that John has Jesus being crucified on Friday, just like the Synoptic Gospels.
If one wants to find a contradiction, they can do it by reading into the text. But once they understand the way ancient historiography works, and take the text into deeper details, they realize that actually John and the Synoptics agree pretty well.