Q. Why do several of the stories told by multiple Gospels have details that seem to be contradictory? I would expect that different authors would bring out different (non-contradictory) details when telling the same story, but there seem to be details that just flat-out can’t be reconciled in some cases. Stories I’m thinking of include the woman who poured perfume on Jesus (did that happen on two occasions?), the time Jesus walked on water, and the time when Judas betrays Jesus in the garden.
You’re right that when the same story is told in more than one gospel, sometimes there are not just differences in which details are included, there are also differences in the specific facts of the story.
For example, when Jesus walks on the water, Matthew includes the detail that Peter wanted to walk on the water, too; Mark and John don’t mention this. Matthew and Mark simply say that the wind died down when Jesus got into the boat; John says that “immediately the boat reached the shore where they were heading.” These could be cases of one gospel writer knowing about something the others didn’t, or at least of one writer choosing to include something the others left out.
But there is another difference in detail between the versions of this story that can’t be reconciled this way. Both Matthew and Mark have the disciples starting across the lake at the end of the day or in the evening, and Jesus walking out to them “shortly before dawn.” In other words, the disciples were on the lake all night. But John says that they saw Jesus approaching the boat “after they had rowed about three or four miles.” We would have to make a deliberate effort to harmonize the stories by insisting, “Ah, the winds must have been so strong and the waters so rough that they were only able to row 3-4 miles all night.” But that’s not what John says, and it doesn’t seem to be his meaning; instead, he depicts the episode as taking place once evening has given way to “dark,” not with dawn approaching. So there is a time difference.
Similar points could be made about the other episodes you mentioned. In Matthew, Mark, and Luke, Judas identifies Jesus in the Garden of Gesthemane by kissing him on the cheek, the customary respectful greeting of the time. But in John, Jesus identifies himself after asking the soldiers, “Who is it you want?” And while all four gospel writers agree that a woman anointed Jesus with perfume in the city of Bethany, and it’s not impossible to reconcile all the accounts to conclude that this took place in the home of a man named Simon, Luke sets the episode early in Jesus’ ministry, while the other gospel writers place it near the end of his life.
But I don’t personally see irreconcilable details such as these as diminishing the truth or authority of the Bible in any way. Rather, as many have observed, these differences actually show that the gospel writers weren’t all trying deliberately to tell the same story as the others. This should give us even greater confidence in the independence and authenticity of their reports. If some minor details differ, the main points are always confirmed. And so we can be confident, based on multiple independent reports, that Jesus did walk on the water–the gospel writers agree about this miracle that testified to who he was. Judas did betray Jesus by bringing the soldiers to the garden. And a woman did anoint Jesus with perfume, and he acknowledged this as an appropriate, if extravagant, act of worship.
We only have problems with the differences in minor details if we embrace the idea that if the Bible is to be the word of God, it has to present only exactly what happened, without dispute or variation, down to the last detail every time. That’s simply not the kind of Bible God has given us. We should recognize that we have instead a Bible whose human character, including such variation in minor details, only helps it to be an even better authoritative witness to divine truth.