Modalism has a definite basis in Scripture, as do most false or deficient ideas about God. In the case of modalism appeal can be made to John 10:30 which says, “I and the Father are one.” And John 14:9 says, “He that has seen me has seen the Father.” Instead of seeing these verses as saying Christ is the second person in the Trinity, and thus a person who is in perfect communion with the Father, the modalist sees Christ and the Father as the same person but appearing in two different forms/modes. But John 10:30 uses the neuter hen in Greek, which means “one deity, one divine essence.” This point is missed by ordinary readers or by those who simply refuse to accept the doctrine of the Trinity because they cannot explain it to their own satisfaction. Jesus is not saying “I and the Father are one and the same person.” He is saying that he is one in essence with the Father and thus he stands in closest relationship with him.
Modalism sometimes arises because a person will not accept the doctrine of substitutionary atonement. But in most conservative circles this doctrine is strongly believed so this has very little to do with the modalism that people unwittingly embrace. It arises, when people do think about the Trinity at all, because they attempt to reduce the mystery of the Trinity to a concept that they can understand and explain with ease. In more conservative circles the loss is, generally speaking, the humanity of Jesus. Make no mistake about it this loss is immense. The longer I live, and the more I listen to conservative Christians talk about God, the more convinced I am that losing the humanity of Jesus has actually left us with a faith that lacks the ability to meaningfully relate the gospel to real human persons.
The first known modalist in church history was a man named Praxeas. It should be clearly stated that Praxeas was a committed follower of Jesus Christ. It is easy for people reading about this today to miss this important point. Fundamentalism has led many to conclude that anyone who holds to a serious error in theology is not a follower of Jesus. History proves this is patently untrue.
Praxeas was a Christian confessor. This meant that he was brought before a judge (in Asia Minor in this case) and openly confessed his faith in Jesus Christ before traveling to Rome in the year 190 A.D. Praxeas opposed the Montanists and their new, prophetic revelations. When he finally arrived in Rome the bishop, a man named Victor, openly welcomed him in his battle to put down adoptionism, a doctrine being popularized by a teacher named Theodotus the Tanner. Praxeas’ emphasis on the full divinity of Christ was a great help to the bishop. But Praxeas also taught that Jesus was God the Father and God the Father was born in time. This aroused the opposition of Tertullian who wrote a book titled: Against Praxeas. Ironically, Tertullian himself later moved into Montanism.
The late Harold O. J. Brown says, “The appearance of modalism in Rome by the last decade of the second century marks the extent of the victory of orthodoxy over Gnosticism, which had been flourishing not many years earlier” (Heresies, 100). Praxeas eventually taught that Christ revealed the Father by actually being the Father. By this means orthodoxy was attacked from the exact opposite end of the spectrum of Gnosticism and adoptionism. To avoid the doctrine that the Father suffered on the cross Praxeas made a distinction between the man Jesus and the Christ, who is God. He reasoned that Christ, who is the Father, adopted the man Jesus and dwelled in him. The struggles of adoptionism and modalism came about because people could not make clear, in their own minds and ideas, what is ultimately a supreme mystery: the doctrine of the incarnation. We must always remember that we can state this truth but we can never explain it in a way that can be completely comprehended by human understanding because revealed truth is always transcendent.