He is obviously not a Christian either. No man can know everything about the planet, ETs/demons, religion and the Bible. If the Bible (and other ancient and historical texts) says humans and demons/aliens formed hybrids, I believe the Bible before Eyespy.
Even Satan believes in God. That doesn't make him a Christian. Christians believe the Bible is God's word and have no hesitations in saying Jesus was the Son of God. Mormons, Jews, JWs, Muslims, Satanists, etc. all believe that God is the creator and that faith is important.