The Logos doctrine was dangerous because it hypostasized the Son beside God, and the Spirit a God beside all of them. A man named Theodotus, a craftsman from Rome, thought that Jesus was a man upon whom the Divine Spirit came in baptism, giving him the power of his Messianic vocation. But this did not make him God.
Therefore these people from the school of Theodotus were very much interested – as were many later, especially Protestants of the 19th century – in those passages of the Gospel dealing with Jesus as man. There is perhaps a connection (Theodotus) and a group in Asia Minor called the Alogoi, who denied the doctrine of the Logos.
And since the doctrine of the Logos appeared in the Fourth Gospel, they rejected it. They tried to find the true text and emphasized the literal interpretation against the allegoric. They were predecessors of many later movements, of the Alexandrian school which fought against some issues, at least, of the high Christology; and they were predecessors of some trends in Rome which always were on the side of the Antiochean school; and they were predecessors of modern liberal theology. They all emphasized the humanity of Jesus over against the Logos becoming God. We call this the adoptionistic or the dynamic Christology, where the man Jesus is adopted and the Logos or the Spirit fills him–but that is all; he is not God Himself. This is the one wing of the Monarchic monotheistic reaction against the Logos Christology.
And this is not something of the past; it is something which we have to face always in the whole history of Christianity. Even in the east these ideas found a representative, Paul of Samosata, bishop of Antioch, and was in the same line. He says: Logos and Spirit are qualities of God, but they are not persons. They are eternal powers, they are potentialities in God, but they are not persons in the sense of independent beings. Jesus is a man who was inspired by this power from above. The Logos power inhabited in Jesus as in a vessel, or as we live in houses. The Logos is the inner man in Jesus. The unity this man Jesus has with God is the unity of will and love, but it is not a unity of nature, because nature has no meaning with respect to God. The more Jesus developed his own being, the more he received. (Finally), he was eternally put into union with God and then he became the judge and received the Divine dignity. Now he is God, but somehow he had to deserve to become God.
This of course is the negation of the Divine nature of the Savior. This shows what made him a heretic, although many people of that time and perhaps even of today would prefer to follow him.