People make the goofiest claims about Jesus and often they do so in trying to saying something important. It is important for pastors — though not just pastors — to revisit early Christian heresies in 2-3 years. They are easy to forget but they are far more present among Christians than many recognize.
Not long ago a local pastor, James Macdonald, had a public conversation with T.D. Jakes, and Jakes has been more than a few times connected with what is called “modalism.” Macdonald’s first response to folks calling him out was not helpful, nor was it informed, and then when TD Jakes was at the event he attempted to clarify his beliefs, though the questions he was pressed on were not to me the best way to ask the important questions.
The point is not Jakes or James; the point is that routine reminders of Christian heresies and informed perceptions of both orthodoxy and heresy would have turned that situation around.
What to read? A good source is Ronald Heine’s Classical Christian Doctrine: Introducing the Essentials of the Ancient Faith. (Another good book on this is by Ben Quash, called Heresies and How to Avoid Them, which I posted about and you can access the posts here.)
What they affirm is that Jesus is God. How do they do this? By arguing that the Father manifested himself on earth as the Son. Father and Son, then, are two different modes in which God manifests himself in the world. “I and the Father are one” means they are the same rather than two in perfect unity. Furthermore, the tendency of this view is that what happened to the Son happened to the Father, with the result that the Son prays to whom? And the Son dies, and that means God dies. And a major issue in the 2d Century, and the final defeater for modalistic monarchianism, was that this means the Father suffers (called patripassianism).
The fuller form of modalistic monarchianism sees the Father present in the OT, the Father present in the Son in his incarnation, and the Father present in the Spirit after Jesus’ exaltation as modes of God’s presence.
A second kind of monarchianism (one God) is called “dynamic” monarchianism. In brief, this view claims Jesus was human but that God’s special power in the Spirit came upon him at his baptism. In essence, Jesus was not God but a human being whom God filled in a unique way.
I hear a kind of monarchianism at times today when folks say Jesus is God only in the sense that God is with us in a special way in Jesus. That Jesus is the sacrament of God for us. This is a kind of dynamic monarchianism (one God) and quite often has roots in Protestant liberalism’s belief that Jesus was the ultimate religious genius but he was only a mere man.