There is no monolith of Christian followers. There are the big segments of those all saying they are Christians, who are adamantly against those of the other big segments. There are those groups of Christians who won't include other Christians among them, over some doctrines that seem really important to them. There are some small churches that even might think they are the only Christians. And for any new controversy with something in question, Christians will divide over it.
This is with one book for God's people, that many of them will claim as their basis of faith. Some still though think they have the only right translation.
This said, the same holds for many groups and movements among humanity. It seems to be a trait characterizing humans, to divide from each other over something or other.
In the 4th century AD, Christianity became the official religion of Rome. This merger altered the original version of Christianity, adding a strong secular element to the once less secular Church. It was no longer the religion of slaves, but a religion also connected to the top of the secular food chain.
As this merger evolved over the centuries, Christianity became more of a hybrid. It was connected to the needs of Jesus, but also connected to a world empire and superpower; shared power. Christianity went from an underdog to an overdog, based on the Roman secular aspects that were integrated into the Church; Vatican. The Holy Roman Empire, became a paradox of opposites; weakness and strength, faith and evidence, poverty and luxury, religion and science, etc.
This hybrid state latest until about the 14th century; 1000 year reign of peace for the hybrid Christianity. This is when the Catholic Church started to divide; Protestant and other movements, with the Roman and the Christian aspects starting to separate, like cellular differentiation during multicellular division; body of the Church went from a hybrid cell, to more like a multicellular body of diverse ratios and blends of Rome and Christianity.
The Atheist movement was heavy on the Roman side of the hybrid, while smaller churches would appear trying to get closer to the pre-4th century Christians ways. This differentiation process is still going on today, forming the body of Christianity. This body now has hands and feet, with each serving a purpose for the whole. Some are down to earth, and some are better in the air. Some are the head and some are the heart. Some are the cerebral; Atheism, and some are the thalamus; spirited, with the thalamus wired to all.