Roman Catholics like to make the point that they are unified, whereas Protestants are not.
To some degree Protestantism exhibits a superficial lack of unity, given that it arose in a particular historical context. Protestants of the Reformation were unified in that they all knew they had to get out of Rome. But they headed in different directions. That’s not the kind of problem that some might think it is. Because most conservative Protestants in our day, now having separated themselves from the theological liberal influences within their midst, (unlike Rome, which has embraced its liberal wing only now to be seen to be changing its mind and cracking down on it) are unified around core doctrines that have always been the core doctrines of historical Christianity.
In the model showing the Churches of the Reformation, salvation is by Christ alone. Christ alone, and Him crucified, is the object of our faith. Explicating this, there is a core of orthodox beliefs, surrounding Scripture, God, Christ, man, sin, redemption, etc. That is, the doctrines explain how Christ brings about this salvation. With some small exceptions, these doctrines, especially for the first 100 years or so after the Reformation, virtually all the big and important doctrines were the same among the Protestant churches. Any differences that existed among these churches were to be found not in the core doctrines, but in some of the peripheral ones. (And the list in the illustration is taken from the order given in many systematic theologies of what is known as “theology proper” -- again, this is not intended to be representative of any one school of thought, but just to be representative of how things worked).
James Anderson has shown, for example, how early Presbyterian and Baptist confessions, to which many conservative Protestants now adhere, are essentially the same document, with minor changes in areas of sacraments and church government. These differences are not central to their faith.
Roman Catholicism, however, as I’ve been showing, puts a façade of unity over top of some deep-seated rifts. I don’t want to make any predictions, but the in the Internet era, in the age of communication, things can happen quickly.
Just sayin’. Stay tuned.