Athanasius of Alexandria (c. 293-May 2, 373), also known as St. Athanasius the Great, was a theologian who later became the patriarch ("pope") of Alexandria, a leader of immense significance in the theological battles of the fourth century. He is best remembered for his role in the conflict with Arianism, although his influence covers a vast array of theological topics.
You conveniently skipped the fact that he was exiled by Constantine and that on his deathbed, Constantine requested baptism be performed by Eusebius who was an outspoken supporter of Arianism, even so far as to being part of Arius' defense at Nicea.
Oh yes. The errors introduced in Christianity start piling up even faster with Constantine and it gets worse century by century until the Reformation of the 1500's made the effort to get back to Biblical Christianity. But even today, even in this thread, you can see people trying to get all the facts from Scripture into their heads to gain a correct understanding.
I don't fault anyone for quoting scriptures and comparing notes with others doing that same thing. I do fault those who make stuff up that is not in the Scriptures. No wonder the average person is so confused.
My only point in listing these example Church Fathers is to demonstrate that the Church emphatically did not start with Constantine. He merely made it the official religion of Rome for the first time. That was nice for those who had been persecuted by Rome the preceding 300 years, but then the corruption begins as the power of the state begins to attract the wrong kind of church leaders - those seeking power and wealth, not truth.