By Peter O'Dwyer
There are many religions that claim to be the "true faith." The Catholic Church, however, towers above the others because She can actually back her claims, unlike the rest. God in His providence has given his Church four marks, or signs, that it is the One True Faith. These four marks are that the Church is one, holy, Catholic and apostolic.
The Church is one in that Her children receive one faith, profess one creed, offer one Sacrifice, and are united under Christ's one Vicar on earth: the Pope. The Church is also one in that She alone is the path to salvation; there are no others.
The Church is holy because She is the spotless Bride of Christ, preserved from error in Her teaching, in Her distribution of graces, and in Her laws. While individuals often fail to live up to the standard, we have Christ's promise that grace will not fail from the top down. The Church cannot teach error, nor can She legislate sin. The flow of grace from the sacraments will never be stopped.
The Church is Catholic, or universal in the Greek, in both scope and mission. The Church encompasses all revelation and teaching from God. Her mission is also universal: to save mankind from Hell.
The Church is apostolic in that it is built on the foundation laid by the Apostles and passes on the teaching of Christ and the Apostles. The Church also enjoys apostolic succession, with Holy Orders being conferred from generation to generation all the way back to the original 12.
The Orthodox have some of these marks, while the Protestants have none. It is only the Catholic Church that is fully and authentically one, holy, Catholic and apostolic.
Watch the full episode: "The Download—The Four Marks."