The whole debate is the result of third or 4th generation (of mostly Gentile) 'Christians' mistaking Gospel narratives as history. Once they went down that path, controversy exploded. Various rationalizations emerged, varying forms of Docetism, Adoptionism and Dyophysitism (and 50 other isms) each offered alternatives for how an ineffable God could also be a man. All of these forms however referred to 'Christ' as God. Even the Arianism that JWs like to point at understood Christ, as Logos, as an emanation of God. Writers like Eusebius often resorted to semantics and even red herring arguments to misrepresent that belief, but that is the nature of sectarianism.
The Second Power concept and the related Logos theology is the keystone to all of this.
Marcionism for example seems a radical departure, but it wasn't really. The central distinction between Marcion's view and Justin Martyr's was the roles assigned the High God and his emanations, Yahweh and Christ. Almost all the theological detail is lost to us, as all we have are snippets from his detractors. However, in the end Marcion too, thought of 'Christ' as God in a sense similar to Justin, or Tatian, or Valentinus, or Eusebius or the author of John. None of these writers agreed in detail but they were all attempting to make sense of the idea of God becoming man.