Nontrinitarianism
Early Christianity

Although nontrinitarian beliefs continued and were dominant among some peoples—for example, the Lombards, Ostrogoths, Visigoths and Vandals —for hundreds of years, the Trinity doctrine eventually gained prominence in the Roman Empire. Nontrinitarians typically argue that early nontrinitarian beliefs, such as Arianism, were systematically suppressed (often to the point of death). After the First Council of Nicaea, Roman Emperor Constantine I issued an edict against Arius ' writings, which included systematic book burning. In spite of the decree, Constantine ordered the readmission of Arius to the church, removed the bishops (including Athanasius) who upheld the teaching of Nicaea, allowed Arianism to grow within the Empire and to spread to Germanic tribes on the frontier, and was himself baptized by an Arian bishop, Eusebius of Nicomedia. His successors as Christian emperors promoted Arianism, until Theodosius I came to the throne in 379 and supported Nicene Christianity.

The Easter letter that Athanasius issued in 367, when the Eastern Empire was ruled by the Arian Emperor Valens, specified the books that belong to the Old Testament and the New Testament, together with seven other books to be read "for instruction in the word of godliness"; it also excluded what Athanasius called apocryphal writings, falsely presented as ancient. Elaine Pagels writes: "In AD 367, Athanasius, the zealous bishop of Alexandria... issued an Easter letter in which he demanded that Egyptian monks destroy all such unacceptable writings, except for those he specifically listed as 'acceptable' even 'canonical'—a list that constitutes the present 'New Testament'".

Nontrinitarians see the Nicene Creed and the results of the Council of Chalcedon as essentially political documents, resulting from the subordination of true doctrine to state interests by leaders of the Catholic Church, so that the church became, in their view, an extension of the Roman Empire. Nontrinitarians (both Modalists and Unitarians) assert that Athanasius and others at Nicaea adopted Greek Platonic philosophy and concepts, and incorporated them in their views of God and Christ.

The author H. G. Wells, later famous for his contribution to science-fiction, wrote in The Outline of History: "We shall see presently how later on all Christendom was torn by disputes about the Trinity. There is no evidence that the apostles of Jesus ever heard of the Trinity, at any rate from him."

The question of why such a central doctrine to the Christian faith would never have been explicitly stated in scripture or taught in detail by Jesus himself was sufficiently important to 16th century historical figures such as Michael Servetus to lead them to argue the question. The Geneva City Council, in accord with the judgment of the cantons of Zürich, Bern, Basel, and Schaffhausen, condemned Servetus to be burned at the stake for this and his opposition to infant baptism.

The Encyclopædia of Religion and Ethics describes the five stages that led to the formulation of the doctrine of the Trinity:
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