Find him in roman records, or letters about ‘this hippie bastard, Christ or something, was a total dick when he came into the office to pay his taxes today. Gods, why do I even do this fucking job? I’m having serious anxiety issues, and at 23, im past middle age. I’m afraid I won’t ever…’ Or literally any reliable source.
Your book about fucking wizards is not a reliable source, and if you get to say Jesus definitely existed; I get to say gandalf actually existed. Also magneto (that even had pictures in the primary source!)