AdoptionismAdoptionism, also called dynamic monarchianism, is an early Christian nontrinitarian theological doctrine, subsequently revived in various forms, which holds that Jesus was adopted as the Son of God at his baptism, his resurrection, or his ascension. How common adoptionist views were among early Christians is debated, but it appears to have been most popular in the first, second, and third centuries. Some scholars see adoptionism as the belief of the earliest followers of Jesus, based on the epistles of Paul and other early literature.
ChristadelphiansThe Christadelphians (ˌkrɪstəˈdɛlfiənz) are a restorationist group that hold a view of biblical unitarianism. There are approximately 50,000 Christadelphians in around 120 countries. The movement developed in the United Kingdom and North America in the 19th century around the teachings of John Thomas, who coined the name Christadelphian from the Greek words for Christ (Christos) and brothers (adelphoi). Asserting the Bible as the sole basis of their beliefs, Christadelphians differ from mainstream Christianity in a number of doctrinal areas.
ArianismArianism (Ἀρειανισμός, Areianismós) is a Christological doctrine first attributed to Arius (AD 256–336), a Christian presbyter from Alexandria, Egypt. 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/made before "time" by God the Father; therefore, Jesus was not coeternal with God the Father, but nonetheless Jesus began to exist outside time as time applies only to the creations of God.
UnitarianismUnitarianism () is a Nontrinitarian branch of Christianity. Unitarian Christians affirm the unitary nature of God as the singular and unique creator of the universe, believe that Jesus Christ was inspired by God in his moral teachings and that he is the savior of humankind, but he is not comparable or equal to God himself. Unitarianism was established in order to restore "primitive Christianity before [what Unitarians saw as] later corruptions setting in"; Likewise, Unitarian Christians generally reject the doctrine of original sin.
NontrinitarianismNontrinitarianism is a form of Christianity that rejects the mainstream Christian theology of the Trinity—the belief that God is three distinct hypostases or persons who are coeternal, coequal, and indivisibly united in one being, or essence (from the Ancient Greek ousia). Certain religious groups that emerged during the Protestant Reformation have historically been known as antitrinitarian.