I don't think so. Here is some info along those lines:
"Christianity was virtually made the state religion of the Roman empire under Constantine. The Church immediately became an institution of vast importance in world politics. Constantine regarded himself as head of the Church. He called the first ecumenical council at Nicea, AD 325, and presided over it. The first world council of the Church."
Christ had designed to conquer by purely Spiritual and Moral means. Conversion was voluntary. But now the military Spirit of Imperial Rome had entered the Church. By forced conversions the Church claimed to have conquered the Roman empire, but in reality the Roman empire had conquered the Church, by making the Church over into the image of the Roman empire.
The Church had changed its nature, had entered its great apostasy, had become a political institution in the Spirit and pattern of Imperial Rome. The Imperial Church of the 4th and 5th centuries had become an entirely different institution from the persecuted church of the first three centuries.
The Church was founded in the Roman empire, and gradually developed a form of government like the political world in which it existed, becoming a vast autocratic institution ruled from the top.
Protestantism was an effort to restore primitive Christianity.
After Constantine adopted Christianity, orthodox Christians like St. Athanasius of Alexandria found themselves persecuted by the Arians.
The monastic movement continued the fight against secular rule over the Church, etc.
Modern Evangelicalism simply DID NOT exist before Constantine.
The Eastern Orthodox monks have continued the tradition of resisting secular authority to this day. So you are oversimplifying things if you try to make it seem that Constantine changed Christian theology.
Ante-Nicene and Post-Nicene theology are much the same.
Do you reject the First Council of Nicaea?