Subordinationism is a heretical doctrine that says the Son and Holy Ghost are subordinate (or less than) the Father in both nature and being. While sometimes confused with Arianism, they are not the same. All Arianists subscribe to Subordinationism, but not all Subordinationalists believe in Arianism. Some see this as the middle ground between Sabellianism and Socinianism/Unitarianism.
Christadelphianism is the name for a 19th-21st century heretical church that follows Unitarianism (making it both antitrinitarian and a Pelagianism-family heresy). They now have churches in 120 countries, but a relatively small membership worldwide. They believe in rebaptism through total immersion and pacifism (Anabaptism), and they deny the Trinity (believing instead in God the Father only). They claim all their teachings are from the inerrant Bible. They believe in Jesus, but as a Father-created being, not eternal God. They believe there is no security in salvation, and that you must keep trying to live a perfect life your whole life. You will not know if you were “good enough” until the Second Coming when all mankind finds out where they spend the rest of eternity—in Hell, or on a new, transformed earth with God (they do not believe in Heaven). The Nazarenes we know today started out as Christadelphians, but separated in the late 19th century.
Ebionitism (coming from a word meaning “the poor” in Hebrew) refers to a Jewish Christian heretical sect of the early church. They regard Jesus as the Messiah and insist that it is still necessary to follow all Jewish laws, traditions and rites (a Legalism heresy). They rejected the writings of Paul as “apostate”. As suggested by their name, they put a high premium on voluntary poverty. Some scholars differentiate Ebionites from groups such as the Nazarenes or Messianic Jews, other considered them the same. Ebionites believe in a Monophysitism-style angelology, claiming that Christ is a great archangel who was incarnated in Jesus and then adopted as the Son of God (quasi-Adoptionism and Psilanthropism).
Psilanthropism is sometimes used to describe Ebionitism, and is considered part of the Adoptionism family of heresies. It teaches that Jesus is “merely human” and is the literal son of two human parents (coming from the Greek for “plain human” or “mere human”). Modern iterations of this heresy include the Unitarian Church (Unitarianism) and the Unification Church.
Unitarianism is an antitrinitarian heresy, beginning in the 16th century, which teaches God is one person, with no distinctness between the Father, Son and Holy Ghost. Sabellianism, on the other hand, simply taught they were different modes in one God (rather than being distinct persons in the Godhead). They believe that Jesus was a prophet and some might even say the “son” of God, but not God himself (an Arianism heresy that is followed by some Unitarians) and that Jesus was born a mere human (Psilanthropism) and, because of his greatness, “adopted” by God (Adoptionism and Socinianism followed by the non-Arianism sect of Unitarianism). They reject the doctrines of Original Sin (humanity is neither inherently corrupt nor inherently virtuous, but capable of both good and evil), predestination, eternal damnation, vicarious sacrifice for atonement, and Biblical Inerrancy (God inspired the work, but humans created errors in recording it), and also deny the virginal birth (Ebionitism). This originally started as a subset of the Anabaptism “radical reformed” movement. They believe that reason, rational thought, science and philosophy coexist with faith in God. They lean towards moderate Universalism in that they believe no one religion has a monopoly on theological truth. The Unitarian ‘church’ still exists today.
Socinianism is a 15th century protestant antitrinitarian heresy that has been embraced by the followers of Unitarianism. Socinianism rejects orthodox teachings of God’s knowledge, the Trinity, the divinity of Christ (elements of Arianism, Ebionitism and Psilanthropism) and salvation. Christ was believed to have not existed before the virginal birth of Jesus (moderated Adoptionism); some Socinianites believed that Joseph was the father of Jesus and rejected the virginal birth. They reject the doctrine of original sin and teach that humans were created mortal and would have died naturally whether or not Adam and Eve ate from the Tree of Good and Evil. Because there is no original sin, they do not believe in the need for atonement. They teach that God’s omniscience is limited to necessary truths (what will definitely happen in the future) and not to contingent truth (what only might happen in the future); they felt if God knew everything that would happen, free will could not exist.
