There are more Christians than there are Catholics.Catholicism has already separated itself from mainstream Christianity by pushing the false concept that the church of Jesus Christ, made up of all born again believers with Jesus in them and them in Him [look it up it's in the New Testament] is wholly contained within the Catholic Church.Can't separate the two.
Oh except for those that are "incomplete." Believing that takes some dedication to false doctrine with strong blinders to the truth on.
Catholicism is the first Protestant denomination because the protested against the Orthodox about a thousand years ago because the Orthodox preferred Jesus as their leader instead of a pope.
More from the cult of all non Catholics are Protestants. Get exorcized from that cult and follow Jesus!
Christians...sans Catholics if you like...use the Bible to have the Truth of what Jesus taught.
If following Jesus and learning His truths is "incomplete" to you, fine with me...
didn't quite happen that way..the schism occured when the eastern church left the original Roman church. However, both eastern and western Catholics are still in communion with one another....some internal things to overcome but both share the same faith essentials.