Simplify the following text for a Grade 10 native English-speaking person.
Original: The Eastern Orthodox Church , the Oriental Orthodox Church and the Roman Catholic Church each regard themselves as the one true and unique church of Christ , and claim to be not just a Christian Church but the original Church founded by Christ , preserving unbroken the original teaching and sacraments . The Roman Catholic Church teaches that `` the one Church of Christ , as a society constituted and organized in the world , subsists in the Catholic Church , governed by the Successor of Peter and the bishops in communion with him .
Simplified: For many hundreds of years , the Roman Catholic Church has regarded itself as the only Christian Church and has called itself the Catholic ( or `` universal '' ) church .