Complex sentence: The Roman Catholic Church, comprising the one Western and the 22 Eastern Rite particular Churches, teaches that the "one, holy, catholic and apostolic" Church "subsists in" the Catholic Church.
Split into simpler sentences: The Roman Catholic Church, comprising the particular Churches including the one Western and the 22 Eastern Rites. The Church teaches that the "one, holy, catholic and apostolic Church" "subsists in" the Catholic Church.