1.1. What is the Catholic Church and why should I be a member of it?
The Catholic Church is the one true Church founded by Jesus Christ, outside of which there is no salvation (extra Ecclesiam nulla salus). It is the Mystical Body of Christ, the Ark of Salvation, possessing the fullness of the means of sanctification and truth. To be a Catholic is to belong to the visible society established by Christ and governed by His divine authority through the Apostles and their successors.
Membership is necessary because Christ Himself commanded,
“He that believeth and is baptized shall be saved, but he that believeth not shall be condemned.”
— Mark 16:16
The Church is the only means He established for the teaching of truth, administration of valid sacraments, and sanctification of souls.