Is Christianity based on older myths?

[Mister Agenda]

I don't care if you believe the events of Jesus' life actually happened or not. But the consequences of rejecting the gospels is that a significant number of people intentionally lied.

That's your claim. Our claim is that none of it is verifiable and even if they were sincere they may well have been wrong.

Then the question is to what end?

No end is needed unless you think intentional fabrication is the only and entire explanation. There are LOTS of possible reasons for information in the Bible to be wrong, possible lying is just one of them.

This all goes toward the probability assessment of whether the first Christians believed in the actual key events in Jesus' life.

Then your first step would be to establish what they believed those key events were prior to the Gospels being written down.