I have no idea which "facts" about Jesus life are historical. I don't read the ancient languages, and I can't get to the source documents anyway. Even if I could, I wouldn't know the professional historical standards for evidence, so I wouldn't be able to make a knowledgeable determination. The scholarly view, as I recall, seems to be that we have a sliver of time, beginning with the sermon on the mount, and ending with the crucifixion that can be regarded as historical.
Mathisen was a Christian literalist (according to him) until a few years ago; now he prefers a more symbolic interpretation of Christianity, which he is explaining interactively right now.