There is no credible evidece for the existence of these alleged churches. Unless you want to claim various heretical churches were the forefathers of your present belief system.
SD
Especially since the Catholic church controlled all of governments where Christians were persecuted for meeting outside the edicts of Catholicism.
The Crusades (another Catholic venture) were nothing in comparison to the Inquisition, where Christians were thrown to something far worse than wild beasts...i. e., the Catholic church.
It's convenient that anything outside of the Catholic church was considered heretical so by definition, all non-catholic churches were heretical.
In reality, it was the catholic church and the popes that were corrupt.