The gospel of John says that Jesus’s disciples still didn’t understand that Jesus was going to rise from the dead… even after Jesus had already risen from the dead.

But all the other gospels say that before he died, Jesus had plainly told them exactly what was going to happen to him. Including that he would be raised to life after three days. So how could they not be aware that it was going to happen?

Possible explanation

The people Jesus trusted to teach everyone his message were idiots who couldn’t understand or remember the most basic things about him, no matter how many opportunities they had to learn those things. (The gospels contain quite a bit of evidence that this was the case, actually…)