Just to add, the idea that everyone should be a member of the Catholic Church for their salvation is straight out of the Bible:
We must be baptized (John 3:3) into the one Body in the one Spirit (1 Cor. 12:13), partake of the one bread as one Body (1 Cor. 10:17), and profess the One Lord, one faith, one Baptism (Eph 4:4-5). Like Noah’s ark, you have to be on board to be saved–as the Bible says, like Noah’s ark in the flood, Baptism now saves (1 Peter 3:20-21), and as I just said, we are baptized into that one Body–so the ark and the Body have the same significance in this regard.
In addition, to have fellowship or communion with Christ in His Body, you must have fellowship with those who have fellowship with Him (1 John 1:3). We are forbidden, therefore, from schisms and dissensions and must be united in belief (1 Cor. 1:10).
Furthermore, while Christ is the head of the Church, He has also willed that the Church be led by men (Acts 20:28). He put St. Peter in charge of His flock (John 21:15-17)–therefore, to be a member of Christ’s flock is to be a member of the flock tended by Peter and his successors.
