Adoptionism is a form of non-triniatrianism and is related to the Arian heresy, which teaches that Jesus was not divine until he was “adopted” at some point during his life (usually at his baptism). In some cases, adoptionists may still not believe in the divinity of Christ. Adoptionism was ruled a heresy by the Synod of Antioch and the First Council of Nicaea.
Although mostly stamped out in the 2nd Century, there was a revival of adoptionism with the growth of the Unitarian sect, which widely held that Jesus was bequeathed the status of divinity and was not the eternal 2nd Person of the Trinity. Certain Mormons, followers of Latter Day Saint heretic, James Strang, also profess this view.