The Feast of the Baptism of our Lord follows the Epiphany because both are events by which God makes his mystery clearer to the human mind. In the Epiphany, the Second Person of the Holy Trinity was worshiped by foreigners who had been led to Bethlehem, but the Magi knew only that the Holy Child was the long-awaited Messiah. Fast forward to the beginning of that Child's mature ministry, and there it is revealed that he is the Second Person of the Most Holy Trinity. Not until he was ascending to Heaven some three years later did he actually name the Trinity, but during the course of those years he gave hints of that triune economy.
The baptism of our Lord was a symbol and not a sacrament because the sacrament of baptism washes away sin, and Christ had no sin. A sacrament actually confers a grace from God, so our Lord's baptism qualifies as a sacramental, which differs from a sacrament in that a sacramental moves the soul to desire the sacraments. There are many sacramentals, and they include holy water, the Rosary, the Liturgy of the Hours, the Brown Scapular, the Miraculous Medal, the Stations of the Cross, the Cross itself, candles, incense, and the Sign of the Cross. Anything blessed would qualify as a sacramental. St. John the Baptist did not use that advanced terminology, but he described it when he said, “I baptize you with water, but he will baptize you with the Holy Spirit” (Mark 1:8).
Various schismatic groups do not make the distinction at all, as they consider baptism symbolic and not efficacious in itself for the remission of sin. Despite this misunderstanding, the Church considers valid any baptism done with water in the name of the Father and Son and Holy Spirit. Conferring a name in baptism signals an intensity in our relationship with God, who “adopts” us as his sons and daughters. Pope Benedict XVI once baptized twenty-one babies in just one month, and said: “Every baptized child acquires the character of the son of God, beginning with their Christian name, an unmistakable sign that the Holy Spirit causes men to be born anew in the womb of the Church.” So it is salutary to be careful in choosing names that identify with the great saints who have gone before us. The first pope to change his name upon election was John II in 533. He did so because his father had named him for the pagan god Mercury. The more pagan a culture becomes, the more it lapses into pagan and even downright silly names. There is, however, the hope that the grace of baptism can make even someone burdened with a fashionably pagan name, a saint. Saint John Vianney said, “Not all the saints started well, but all of them ended well.”