One form of Monarchianism originated with Paul of Samosata, the bishop of Antioch. He was known for his flamboyant preaching style and for requesting applause for his sermons. During the service, he had a female choir singing hymns to praise him. He also managed to amass a large fortune without inheriting money or conducting a business, which aroused some suspicion about him. He taught that Jesus was not divine, but merely a man who had achieved divinity through personal righteousness. This is called Adoptionism or Dynamic Monarchianism.
There is strong evidence that early Christians also shared this view of Christ as the Jehovah of the Old Testament, as I discuss more fully on my page about " Questions on Relationships Between God, Man, and Others ." For example, non-LDS scholar Margaret Barker recognizes the "overwhelming" evidence that early Christians identified Christ with Jehovah in the Old Testament, and in doing so, addresses the issue of how they understood Deut. 6:4. The following excerpt is taken from her book, The Great Angel: A Study of Israel's Second God (London: SPCK, 1992, pp. 192-193, as cited by Kevin Christensen, Paradigms Regained: A Survey of Margaret Barker's Scholarship and Its Significance for Mormon Studies , FARMS Occasional Papers (Provo: FARMS, 2001), pp. 24-25):