The Sacrament of Baptism: Gateway to New Life
The sacrament of Baptism is the beginning of life—supernatural life. Because of original sin, we come into the world with only the natural endowments of human nature. The supernatural life, which is the result of God's personal and intimate indwelling, is absent from the soul. Original sin is not, in the strict sense, a "blot" upon the soul. Indeed, original sin is not a "something" at all. It is the absence of something that should be there. It is a darkness where there ought to be light. Jesus instituted the sacrament of Baptism to apply to each individual soul the atonement which He made on the Cross for original sin. Jesus will not force His gift upon us, the gift of supernatural life for which He paid. He holds the gift out to us hopefully, but each of us must freely accept it. We make that acceptance by receiving the sacrament of Baptism.
When the sacrament of Baptism is administered, the spiritual vacuum, which we call original sin, disappears as God becomes present in the soul, and the soul is caught up into that sharing of God's own life, which we call sanctifying grace.
Children of God
The sacrament of Baptism not only gives us sanctifying grace, it also makes us adopted children of God and heirs of heaven. We say "adopted" children because God the Father has only one begotten Son—Jesus Christ. He is God's only Son through generation; the rest of us become God's children by adoption. As children of God, we receive our inheritance at the very moment of our adoption, at the very moment of Baptism. Our inheritance is eternal union with God, and we have that inheritance now, once we are baptized. Nobody can take this inheritance away. Not even God, who has bound Himself by irrevocable promise never to take back what He has given. We ourselves can renounce our rights—as we will do if we commit mortal sin—but no one else can deprive us of our heritage. The point to be emphasized, and never to be forgotten, is that we are potentially in heaven the moment we are baptized.
The mark of a Christian
Several things happen to us when we are baptized. We receive the supernatural life, called sanctifying grace, which dissipates the spiritual emptiness of original sin. And there is imparted to the soul a permanent and distinctive quality which we call the character or the mark of Baptism. Precisely because we possess the baptismal character, we have the right to receive the other sacraments. None of them can mean a thing to us until first the capacity for receiving the other sacraments has been established in the soul by the character of Baptism. This is because it is by the character of actual Baptism that we "put on Christ," in the words of St. Paul. It is the character of Baptism, according to St. Thomas, that "configures" us to Christ and makes us participants in His eternal priesthood. By Baptism we are given the power—and the obligation—to share with Christ in those things which pertain to divine worship: the Mass and the sacraments.
We enter the Church
The impression of the baptismal character upon the soul also makes us members of the Church. The "mark" of Baptism is what differentiates between those who are members of the Church, Christ's Mystical Body, and those who are not. This membership also imposes upon us an obligation to discharge the duties that go with our being configured to Christ and our membership in Christ's Church. This means to lead a life according to the pattern that Christ has given us, and to give obedience to Christ's representatives, our bishops and especially our Holy Father the Pope.
Baptism is necessary for salvation
Baptism is necessary for salvation for anyone who has heard the Gospel of Christ and has the possibility of requesting Baptism. "Unless a man be born again of water and the Spirit, he cannot enter into the kingdom of God," Jesus told Nicodemus (John 3:5). And His command to the Apostles was: "Go into the whole world and preach the Gospel to every creature. He who believes and is baptized shall be saved, but he who does not believe" (and, by inference, is not baptized) "shall be condemned" (Mark 16: 15-16). (The Catechism's section on Baptism also describes this requirement; see numbers 1257-1261).
Infant baptism
The historic Church has always held that Christ’s law applies to infants as well as adults, for Jesus said that no one can enter heaven unless he has been born again of water and the Holy Spirit (John 3:5). His words can be taken to apply to anyone capable of belonging to his kingdom. He asserted such even for children: "Let the children come to me, and do not hinder them; for to such belongs the kingdom of heaven" (Matt. 19:14). The Lord did not require them to make a conscious decision. He says that they are precisely the kind of people who can come to him and receive the kingdom. Furthermore, Paul notes that baptism has replaced circumcision (Col. 2:11–12). In that passage, he refers to baptism as "the circumcision of Christ" and "the circumcision made without hands." Of course, usually only infants were circumcised under the Old Law; circumcision of adults was rare, since there were few converts to Judaism. If Paul meant to exclude infants, he would not have chosen circumcision as a parallel for baptism.
This comparison between who could receive baptism and circumcision is an appropriate one. In the Old Testament, if a man wanted to become a Jew, he had to believe in the God of Israel and be circumcised. In the New Testament, if one wants to become a Christian, one must believe in God and Jesus and be baptized. In the Old Testament, those born into Jewish households could be circumcised in anticipation of the Jewish faith in which they would be raised. Thus in the New Testament, those born in Christian households can be baptized in anticipation of the Christian faith in which they will be raised. The pattern is the same: if one is an adult, one must have faith before receiving the rite of membership; if one is a child too young to have faith, one may be given the rite of membership in the knowledge that one will be raised in the faith. This is the basis of Paul’s reference to baptism as "the circumcision of Christ"—that is, the Christian equivalent of circumcision.
As well, we read in the New Testament that Lydia was converted by Paul’s preaching and that "She was baptized, with her household" (Acts 16:15). The Philippian jailer whom Paul and Silas had converted to the faith was baptized that night along with his household. We are told that "the same hour of the night . . . he was baptized, with all his family" (Acts 16:33). And in his greetings to the Corinthians, Paul recalled that, "I did baptize also the household of Stephanas" (1 Cor. 1:16). In all these cases, whole households or families were baptized. This means more than just the spouse; the children too were included. For parents, this means that they should not unduly delay the Baptism of their newborn child.