What man was that?  I've heard of Jesus Christ walking on water.  A being fully God and fully man.  Just a man, no.  Eye witness accounts of the miracles and life of Jesus Christ, written during the life of Jesus Christ exist in the thousands.   One or two written manuscripts of Homer's Illyid exist and there is not doubt of his existence, and Troy was rediscovered and accepted.   I fail to see the rationality in the belief that everything came from nothing.