The practice of Christianity has had many different priorities over the centuries, and most of those splits have had to do with some combination of theological, political, nationalistic, etc. priorities.

We treat other books thusly too--we highlight what we think is important and minimize what we think isn't. Like, it is Christmas Eve--think of just how many adaptations of A Christmas Carol there are.

With the church, those differences have felt much more dramatic because we so often say that salvation is at stake, persecute the losers, and so on, to our detriment and disrepute.