The two were once one so originally there was no separation, and originally it was just the “Christian Church.” The Orthodox church is considered the original church now because they follow more of the old traditions than Roman Catholics do; more changes happened in the Catholic church after the east west schism than Dec 17, 2018
Who is the leader of the Protestant Church?
Martin Luther, often called the father of Protestantism, fundamentally changed the Christian world through his force of will and new ideas. He tried passionately to reform the Catholic Church.