Ask him if he believes ANY of the Bible! How can he pick and choose what parts to believe when it was the Holy Ghost who inspired all of it?
2Pe 1:21 For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.
I questioned him on that since he kept saying, "prove to me where Jesus said that God wrote the Bible," and he never answers. He goes off on another issue. I think the guy is extremely stubborn in his ways and refuses to accept proof, even when it's given to him. It's sad really.