The purpose of the sacraments is to sanctify men, to build up the Body of Christ, and, finally, to give worship to God. Because they are signs they also instruct. They not only presuppose faith, but by words and objects they also nourish, strengthen, and express it. That is why they are called sacraments of faith.
–Catechism of the Catholic Church, #1123
St. John the Evangelist 