Psilanthropism is a heresy that teaches Jesus was the product of a sexual union between two human parents. The word is a combination of ψιλός and ἄνθρωπος, meaning “bare human.” Psilanthropism is a subset and close relative of Arianism, although Arianism usually contains some theistic influence (at least eventually) in their Christology, while Psilanthropists deny deity altogether.
It is a rare heresy, but is present among Unification Church and few others sub-christian groups. It is more popular among false religions that consider Christ a prophet, but not God.