By this time, it was Trinitarians arguing with Trinitarians. The Trinity, evolved over time in a long process, was now presupposed. Many non-Catholic Christians, such as myself, consider the Papacy a religio-political tyrant, a form of totalitarianism that ruled Europe for a thousand years. It being obviously an impostor, certainly not the Christianity that Christ founded, it brings much suspicion that there must be something fundamentally wrong with the Trinitarian foundation the system is built upon. There is.
So why fuss about Nestorius? The problem lies further back. These people arguing here about Christ’s nature were the “wise and prudent” Christ referred to, Matt. 11:25-27.
No man knoweth the Son, but the Father; neither knoweth any man the Father, save the Son, and he to whomsoever the Son will reveal him.
They didn’t have a clue, the answer lies in the revelation of the Father and Son, which was hidden from their eyes, verse 25, thou hast hid these things from the wise and prudent, it was hidden from their eyes. The mystery of the incarnation is a GREAT mystery, how the one true God the Father, an individed unity, could be united with humanity, was beyond the capacity of these “wise and prudent.” The key to it they had long ago rejected.
And without controversy GREAT is the mystery of godliness: God was manifest in the flesh, 1 Tim. 3:16.
The Papacy was there from the beginning, my friend, you're making things up. Constantine legalized the Catholic Faith helping it spread. You apparently think that Christ has not the power to keep his Church true to his teachings which makes him a mere man and not God. Do you actually think Christ would establish a Church without a leader. What has actually morphed from the Catholic Church is the uncountable denominations claiming the guidance of the Holy Spirit who apparently can't keep them all believing the same thing. There is ONE Faith, ONE Baptism.