What most folk seem to get wrong about the origins of Christianity

I’m not going to write a huge essay here, since most folk wouldn’t even bother reading it (I know from experience)… so instead, I’m going to ask a simple question which I intend as a challenge to anybody who believes in the historical Jesus:

What is your best evidence that Paul knew about the teachings of Jesus as presented in the stories of Jesus of Nazareth that showed up after his death?

Then we can thrash out stuff about loving your neighbour and drinking Jesus’ blood in the discussion…