This is what what we’ve got so far:

Human behaviour is controlled by beings from an invisible, undetectable spiritual realm. We know this invisible, undetectable spiritual realm exists because of the effect it has on human behaviour (even if dumb old atheists can’t wrap their minds round the fact.)

Circular reasoning, not evidence.

The synoptic gospels rely on an earlier oral tradition. We know there was an earlier oral tradition because the synoptic gospels rely on it.

Circular reasoning, not evidence. (The same applies to Q.)

We know the stories about Jesus are indisputably true because they’re in the gospels that no-one at the time disputed. We know the gospels are indisputably true because they tell us stories about Jesus that at the time no-one disputed.

Circular reasoning, not evidence. There is no corroborative, independent evidence for any of the stories about Jesus. (I’ll get to the indisputable claim soon.)