A follower of Eutyches in the belief that the divine and the human in the person of Christ so blend as to constitute but one nature so that Christ is of two natures but not in two : monophysite
At Council of Chalcedon in 433. The assembled bishops declared Christ was two natures in one person. “We all with one voice confess our Lord Jesus Christ one and the same Son, at once complete in manhood, truly God and truly man, consisting of a reasonable soul and body; of one substance with the Father as regards his Godhead, of one substance with us as regards his manhood, like us in all things, apart from sin…”
Arian theology holds that Jesus Christ is the Son of God, who was begotten by God the Father with the difference that the Son of God did not always exist but was begotten within time by God the Father, therefore Jesus was not co-eternal with God the Father.
Docetism is an ancient heresy that says Jesus was not fully human. According to Docetism, he seemed to be human, but because Jesus was fully divine, he had no physical body. The form people saw was essentially a ghost.
They believed in one God and taught that Jesus was the Messiah and was the true “prophet” mentioned in Deuteronomy 18:15. They rejected the Virgin Birth of Jesus, instead holding that he was the natural son of Joseph and Mary. The Ebionites believed Jesus became the Messiah because he obeyed the Jewish Law.