Nestorian, Socinian, Arian, Trinitarian, Modalist. Differences of view over the unity of God, and the deity and nature of Christ. This should come as no surprise that there would be a struggle over these crucial matters, any more than the many other differences of view in other Christian disciplines, such as in eschatology: Preterist, Historicist, Futurist, Dispensationalism, Premillennialism, Amillennialism, Postmillennialism.
Same with differences of leadership and authority. Protestants sharply disagree with the RCC over the primacy of the Popes, and Mormon “Apostles,” etc.
Most of us Biblicists could care less about Constantine, the councils of men, the Pope, Mormon Apostles, or anything else that sets itself up as the last word on Christian truth. It is for the individual Christian to seek out and find for himself.
Its an in house thing among us Christians, none of which has anything to do with you as an Ingersoll quoting Atheist.
A question, not necessarily addressed to you:
Why is an atheist on the "Religion Forum"? They claim to have no religion, could it be that atheism is their religion?