It’s often alleged that the sort of detailed resurrection accounts we find in Matthew, Luke, John, and Acts didn’t develop until decades after Jesus’ death. We’re often told, for example, that the gospel of Mark doesn’t have any resurrection appearances, which supposedly implies that the author of the gospel was unaware of such accounts or rejected any he was aware of.
But we find accounts of resurrection appearances as early as the material Paul cites in 1 Corinthians 15:3-8, which probably dates to the 30s. And while Mark’s gospel doesn’t narrate any resurrection appearances, it does anticipate them (14:28, 16:7), and it does so in such a way that they were considered past events at the time the gospel was written. The author wasn’t agnostic or skeptical about whether what Jesus anticipated in 14:28 and what the angel anticipated in 16:7 occurred. From the author’s perspective, what was anticipated would and did happen. So, while Mark’s gospel doesn’t narrate resurrection appearances, it does refer to one or more appearances as a historical fact.
And the appearances in 1 Corinthians 15 and Mark are of a significantly detailed nature. 1 Corinthians 15 gives us information about who was and wasn’t involved in the appearances, individual and group names, and the chronological order of the events, for example. In some ways, 1 Corinthians 15 is more detailed than what we get in Matthew, Luke, John, and Acts. Mark specifies who Jesus will appear to, with an emphasis on Peter, that the appearance(s) will happen soon, and where.
There’s no reason to expect sources like 1 Corinthians 15 and Mark’s gospel to provide the sort of lengthy narratives we find in Matthew, Luke, John, and Acts. Paul is citing a brief, summarizing creed in 1 Corinthians 15, without much added to it, and Mark is citing anticipations of the resurrection appearances on the part of Jesus and an angel. Why should we expect contexts of such a non-narrative nature to provide the sort of lengthy narratives we find elsewhere?
It would be absurd to suggest that Paul doesn’t say more in his letters about his experience with the risen Christ because he was ignorant of the details or uninterested in them. Rather, there are contextual reasons why he doesn’t say more. He was writing letters, not autobiographies, and he was largely writing to people who already had some familiarity with his background. When he wanted to mention his background for one reason or another, he did it in brief, summarizing form. It doesn’t follow that the brief, summarizing form was all he knew or all he was concerned about. Similarly, how much he says about resurrection issues varies from one letter to another. He says more about resurrection issues to the Corinthians than he does to the Thessalonians, since matters pertaining to the resurrection were more relevant to what he was writing to the Corinthians about and his correspondence with them was lengthier.
Not only do we see earlier sources, like Paul, saying less than they knew and less than they were concerned about regarding Jesus’ resurrection, but we see the same with later sources. See here.
And I’ve argued, such as in the recent post here, that there’s good evidence for the historicity of the appearance narratives in Matthew, Luke, John, and Acts. See here regarding how well those accounts align with 1 Corinthians 15. See here concerning the consistencies among the resurrection accounts more broadly.