I think each denomination or movement was started when a specific point came to life. For example,
Lutherans, with Luther's understanding of "The just shall live by faith."
Baptists, with the emphasis on the finished work of the cross.
The Charismatic movement that sprang from the Azusa Street event,
... and so forth.
There are core doctrines of Christianity that are not negotiable, such as the Triune God, deity of Yeshua, salvation by faith, the virgin birth, etc. These are essential in defining the Christian faith.
Then there are peripheral doctrines, such as interpretation of prophecy, gifts such as "speaking in tongues", and so forth that in themselves don't define what basic Christianity is.
In the essential doctrines the various Christian denominations have unity. In the non-essential doctrines we have liberty.