See the wikipedia article for the various manifestations, variations, and proponents of Adoptionism throughout history. See Catholic Encyclopedia article (Adoptionists section) describing how the early church dealt with the leader of the sect: Theodotus of Byzantium.
A well written medium article explained how a case for Adoptionism can be made based 1) "minority" textual variants of Luke 3:22 and other verses related to Jesus's earthly father (Joseph), 2) ancient Jewish understanding of how the King is a Son of God, 3) seeing Jesus's baptism as coronation similar to the symbolism of the doves in the Roman transfer of power from Caesar to Augustus, 4) contemporary Roman imperial cult of adoption Caesar's adoption of Octavian.
Question: What were the arguments they used to refute adoptionism?
The purpose of this question is to
- investigate whether non-NT sources were used in the arguments
- learn how the church fathers use and interpret the NT passages to establish Jesus's pre-existent deity
I'm looking for quotes from any of the following:
- declarations issued by the 2 Popes,
- writings by early church theologians, or
- council documents (not necessarily the 798 AD council, if adoptionism happened to be addressed at an earlier council)
Accepted answer needs to show how the quotes contribute to the refutation as well as the source of the quotes.
Motivation for this question
This question is motivated by some groups (like Jehovah's Witnesses) who do not think that NT books on its own is sufficient to establish the pre-existence and the God nature of Jesus, although hints are there (see answer to another question).
This question is related to a larger-scope question about how the church fathers refined the Trinitarian formula. But this question focuses only on refutation of Adoptionism.