The gospel of John says John the Baptist saw the Holy Spirit in the form of a dove descend on Jesus. And it says the next day, John the Baptist saw Jesus passing by again.

But according to the gospel of Mark, as soon as the Spirit descended on Jesus, it sent him out into the wilderness at once, and he stayed there for 40 days.

Possible explanations

It does say John was in the wilderness already, so being out in the wilderness isn’t incompatible with being with John. But it sure doesn’t sound like it’s saying Jesus stayed with John, among huge crowds of people who were coming to be baptized. It sounds like Jesus went away from where he had been, going “out into the wilderness” somewhere else, where he spend 40 days alone with only wild animals, angels, and the devil for company. I’ve never heard of any Christians interpreting this as Jesus staying right where he was among the crowds with John for 40 days.

Another possibility is that the events in John 1 are after Jesus has come back from his 40 days in the wilderness, and John the Baptist is talking about having already met Jesus and seen the dove back before that. And he’s talking to people who weren’t there when that happened.