For the first 300 years after Christ there was only one church, some called it the Way, and others simply called it the church. We read of these churches called by the town they were in, such as the Corinthian church. They made up the age of the apostles, as they were taught and led by the men Christ chose, the apostles. If they had a problem with differences in understanding or did not understand something they took it to the church closest to the teaching of the original apostles.
Constantine changed all this. Problems were solved by a council, and the reasoning of men solved the problem instead of going to the authority that the church felt was closest to the apostles. The Catholic church evolved from the rule of Constantine.
The churches of the first 300 years were very careful that they neither added to or changed doctrines of the church. They carefully saw that there were no changes. Constantine changed this at the council of Nausea, giving men authority to add to the church doctrine, so even language was used that was not from scripture. That was never so in the first churches.
Man keeps adding to church doctrine little by little, so by the age of the reformation the church was almost spiritually dead. A major symptom of this was the sale of indulgences. Luther changed this to a certain degree. For the next several hundred years different men tried to take the church back to its beginning, like the Anabaptist and John Westley.