score:5
I think this is a logical mistake more than a theological mistake, and I don't think this is a named heresy. If anything, it seems like a violation of the communication of properties; something reminiscent of patripassianism.
The Shield of the Trinity (see below) is basically a picture version of the communication of properties, which sets up the background:
The equality is based on ontology and essence (h*m*ousia), and their inequality is based on their function and their personhood (hypostasis). The former is required of a monotheistic God, and the latter is required of a Triune God.
The relavent logical principles are the law of non-contradiction and law of identity.
Combining these:
The topics of the eternal generation of the Son and the procession of the Holy Spirit are related and also discussed in the resources below. They help draw out the ideas of Jesus being the Son and the relations between the persons of the Trinity, etc.
Resources:
Systematic Theology by Augustus Hopkins Strong
Dogmatic Theology by W.G.T. Shedd
Shield of the Trinity:
Upvote:5
I think this could be considered a type of modalism: the belief that there is only one person of God, who appears in different times or contexts as the father, son, and holy spirit, but does not by nature have true relations between these. In modalism, "father" and "son" are only labels for human benefit, not true descriptions of how God is, and so you could get the nonsensical conclusion that Jesus is his own son.