Simplify the following text for a Grade 7 native English-speaking person.
Original: The Nicene Creed has been normative to the Anglican Church , Eastern Orthodox Church , Assyrian Church of the East , Oriental Orthodox churches , the Roman Catholic Church including the Eastern Catholic Churches and the Old Catholic Church , the Lutheran Church and most Protestant denominations .
Simplified: This clause is one of the main differences between the Roman Catholic Church and the Eastern Orthodox Church . The Catholic Church has this clause , the Eastern Orthodox Church does not .