5 But this is not all. Christ reigns nor only by natural right as the Son of God, but also by a right that He has acquired. For He it was who snatched us "from the power of darkness" (Colossians i., 13), and "gave Himself for the redemption of all" (I Timothy ii., 6). Therefore not only Catholics, and those who have duly received Christian baptism, but also all men, individually and collectively, have become to Him "a purchased people" (I Peter ii., 9). St. Augustine's words are therefore to the point when he says: "You ask what price He paid? See what He gave and you will understand how much He paid. The price was the blood of Christ. What could cost so much but the whole world, and all its people? The great price He paid was paid for all" (T. 120 on St. John).
Source: Annum Sacrum (Vatican.va)