Nontrinitarism is a movement that rejects the idea of the Christian Trinity. That idea says that God is three different persons in one being.
There are several movements which can be classified as Nontrinitarian. At the First Council of Nicaea, in the year 325, people met and defined the idea of trinity. Some movements started before the council.[1] Nontrinitarianism was later renewed in the Gnosticism of the Cathars in the 11th through 13th centuries, in the Age of Enlightenment of the 18th century, and in Restorationism during the 19th century.
Modern-day versions are usually called Unitarianism.
[In the 2nd century,] Jesus was either regarded as the man whom God hath chosen, in whom the Deity or the Spirit of God dwelt, and who, after being tested, was adopted by God and invested with dominion, (Adoptian Christology); or Jesus was regarded as a heavenly spiritual being (the highest after God) who took flesh, and again returned to heaven after the completion of his work on earth (pneumatic Christology)