1. The Catholic Church teaches that baptism or the desire for baptism is essential for salvation (see DS 1524/796, 1618/861).19 This is the same as the demand that one accept the Lord Jesus (by whom alone we are saved), that one have faith (which is the acceptance of Jesus), or that one enter the Church (which is the communion of those who accept Jesus and the community where those who seek Jesus find him).20
This teaching has been repeated very clearly by Vatican II. The missionary activity of the Church
. . . finds its reason in the will of God, “who wishes all men to be saved and to come to the knowledge of the truth. For there is one God, and one mediator between God and men, himself man, Christ Jesus, who gave himself a ransom for all” (1 Tm 2.4–6), “neither is there salvation in any other” (Acts 4.12).
Therefore, all must be converted to him as he is made known by the Church’s preaching. All must be incorporated into him by baptism, and into the Church which is his body. For Christ himself “in explicit terms . . . affirmed the necessity of faith and baptism (cf. Mk 16.16; Jn 3.5) and thereby affirmed also the necessity of the Church, for through baptism as through a door men enter the Church. Whosoever, therefore, knowing that the Catholic Church was made necessary by God through Jesus Christ, would refuse to enter her or to remain in her could not be saved.” (AG 7; cf. LG 14)
2. Baptism is personal union with Jesus (see S.t., 3, q. 68, a. 1; q. 69, a. 5). Everything else follows from this. Our Lord in glory is the new covenant, the new and everlasting bond uniting God and humankind. Sin is separation from God; baptism overcomes sin, for one who is united with Jesus cannot be separated from God. Baptism means receiving the Spirit and the charity he pours forth in one’s heart; one shares in the Spirit by being united with Jesus whose Spirit he is (see DS 1530/800). Those who accept Jesus abide in him and the Father, who send the Spirit and abide in all who are united with Jesus. As a result, human persons are similarly bonded with one another (see Jn 17.20–23). Thus the Church is formed, for those who are members of the Lord Jesus and children of God are members of one another and brothers and sisters in the same divine family (see 1 Cor 12.12–13, 23–27).
3. Because one receives faith in baptism and by it is united with Jesus (see Gal 3.26–28), baptism makes one a child of God. Adam’s children are reborn in Jesus (see DS 1523/795). Buried with him (see Col 2.12), they are reborn from the water of baptism, not as from the waters of a natural womb—to a merely human life—but as new people and part of a new creation (see 2 Cor 5.17; Eph 2.15–16). Baptism truly is a new birth (see Jn 3.5; Ti 3.5; 1 Pt 1.3); therefore, it gives one a new heart—a new inner self, a new personal being (see Is 32.15; Jer 31.33; Ez 36.26; Jl 3.1–2).
4. The new person one becomes by baptism is not simply a new and better self. One is clothed with Jesus (see Gal 3.27), one becomes the new man who is Jesus (see Eph 2.15; 4.24). He unifies all creation, first of all by forming his Church (see Col 3.10–11; also LG 7 and 8). Thus the baptized form in him one body, the Church (see 1 Cor 12.27).
As Vatican II teaches, through baptism as through a door, men and women, as well as infants, enter the Church (see LG 14), for the Church is the communion of those who make up God’s family by being united with Jesus (see LG 8–11). “Thus, by baptism, men are united to the paschal mystery of Christ: they die with him, are buried with him, and rise with him (cf. Rom 6.4; Eph 2.6; Col 3.1; 2 Tm 2.11); they receive the spirit of adoption as sons ‘by virtue of which we cry: Abba, Father’ (Rom 8.15), and thus become those true adorers whom the Father seeks (cf. Jn 4.23)” (SC 6; translation amended). Jesus is the mediator. By communion with him, one comes to the goal of baptism: adoption as a child of God.
5. Baptism into the Lord Jesus is baptism into his reality, a sharing in his Spirit (see Jn 3.1–21). This central truth about the Christian has already been treated at length. Those who form Jesus in his Church are God’s adopted children, really sharing Jesus’ status by the gift of his Spirit, who pours forth God’s love into their hearts (see Rom 5.5; 8.14–17). The present gift of the Spirit is, as it were, a down payment (see Eph 1.13–14) on the full experience of divine family life which they shall enjoy as the fruit of Jesus’ death (see 1 Jn 3.1–2). Inasmuch as the Spirit is the soul of the Church (see LG 7), baptism makes them one not only in body but in soul.
6. By baptism we are so closely united with our Lord that we already share in his resurrection and glory, although in an invisible way (see Eph 2.5–6; Col 2.12; 3.1–4).21 Our dignity as divine children, to whom immortality and heavenly fulfillment are due, is not only future but present, waiting only to be revealed (see Rom 8.18–19). At the same time, resurrection is not yet complete in us (see 1 Cor 15.20–23). For the present, our resurrection is evidenced in this: We should and can live the life of good deeds which God has prepared for us (see Eph 2.6–10).
7. The special character received in baptism is something like citizenship in a political society. As members of the Church, the baptized are entitled not only to receive the Eucharist and everything else the Church has to give, but to share in common actions—that is, to participate in offering the Eucharist and in other acts which the Church does in common.
8. Jesus has given those who accept him the power to become children of God (see Jn 1.12–13). This power, as St. John Chrysostom suggests, is like that of an agent. It enables one who is being baptized both to become and to behave as a child of God.22 If this insight is correct, an adult in receiving baptism both receives and exercises the baptismal character, both becomes a member of the Church and acts in that role, both receives the gift of living faith and commits himself or herself to Jesus with this faith.
9. As life is in a sense the most important human good, since only those who live can seek and enjoy other goods, baptism is in a sense the most important sacrament. Christian life as a whole is present here in embryonic form. For baptism unites one with Jesus in his Church and confers the grace of divine adoption. The other sacraments add nothing extrinsic, but rather, in their distinct ways, develop to full maturity what is present in embryo in baptism (see S.t., 3, q. 65). This explains why those whose lives are cut short (for example, an infant who dies soon after baptism) and those who blamelessly fail to appreciate the fullness of Catholic truth (for example, Protestants of good will) can enjoy a true sacramental life by baptism alone.
10. The embryonic richness of baptism is unfolded in the fullness of mature Christian life: into the fullness of the gift of the Spirit in confirmation, the fullness of communion with Jesus in the Eucharist, the fullness of overcoming sin and its effects in penance and anointing, the fullness of sharing in Jesus’ priesthood in orders, and the fullness of the interpersonal communion of the members of Jesus’ Body in matrimony. This no more detracts from the beauty and richness of the total gift received in baptism than appreciation of the physiology of an adult organism reduces one’s sense of wonder at the perfection of the embryo, where all that will be is already present in its beginnings.
By baptism, sinful human persons are united with our Lord in glory, and so their sin (separation from God) is overcome (see S.t., 3, q. 69, aa. 1–2). In Jesus, God’s natural Son, they become adopted children of God, called to a life in this world and in eternity appropriate to their new being as members of the divine family.
In two passages in Colossians one finds the entire theology of baptism (see Col 2.9–14; 3.1–6). A movement of turning toward Jesus, which is aroused by the preaching of the gospel and the grace of the Spirit, brings one to baptism. There one receives living faith, which is a sharing in the communion with God. This communion is the new covenant, established in Jesus by his redemptive act and God’s redeeming response to it. This covenant with God wipes away sin and makes one share in the fullness of deity present bodily in Jesus. In consequence, one has died to the former sinful life of fallen humankind; one has a new life to lead.
Certain aspects of this complex whole—the preaching of the gospel, conversion to Jesus, faith, and the forgiveness of sin—deserve further discussion.
From the point of view of the Church, the liturgy is not the whole of her work, but is its heart. To prepare people for participation in the Eucharist, the Church first must bring them in baptism to living faith. To do this, she must first preach the gospel of repentance and faith (see SC 9). As St. Paul teaches, faith in the heart justifies, but faith comes into one’s heart only by the acceptance of the gospel, and one cannot accept it unless it is preached by those commissioned to do so (see Rom 10.10–17).
Conversion essentially is a turning toward the dawn which arises in the darkness, a dawn which is liberating (see Lk 1.78–79). One need only accept this new light in order to receive the power to become a child of God—not a servant, but a friend and member of the divine family (see Jn 1.12–13; 15.15). Jesus did not come to condemn the world, but to judge it mercifully, if only the world will accept him in faith (see Jn 3.17; 5.22–30; 12.47). Hence, the announcement of the kingdom and the call for repentance must be understood as a summons to mercy: “Awake, O sleeper, and arise from the dead, and Christ shall give you light” (Eph 5.14).
According to Trent’s definitive teaching, a person capable of acting who hears the gospel and does not resist the grace of the Spirit is turned and turns toward God, by preliminary human dispositions of imperfect faith, hope, and love which prepare for baptism (see DS 1526–27/798, 1557–59/817–19). Grace is primary, but one can and must cooperate with it (see DS 1525/797, 1554/814). Thus it is correct to regard conversion both as the sinner’s act: “Return to me, says the Lord of hosts, and I will return to you, says the Lord of hosts” (Zec 1.3), and as God’s act: “Restore us to yourself, O Lord, that we may be restored!” (Lam 5.21).
The call to conversion which the Church proclaims is a call to penance and the remission of sins (see Mt 28.16–20; Lk 24.47), and for this very reason it is an invitation to baptism. In baptism, the preliminary dispositions of conversion are accepted by the Church as the token of one’s willingness to be united with Jesus. The person baptized receives perfect, living faith and hope, together with the love of God which is poured forth by the Holy Spirit (see DS 1528–30/799–800). Faith and baptism are closely bound together (see Mk 16.16; Acts 8.11–12; Gal 3.26–27; Eph 4.5; Heb 10.22–23). Acceptance of the gospel brings one to baptism; baptism itself makes one’s acceptance of the gospel into a personal acceptance of the truth and love of God, a real beginning of eternal communion in the new covenant of Jesus.23
Therefore, it is in baptism itself that sin is taken away (see Col 2.13–14). Faith brings the remission of sin only insofar as it brings one to new life in Jesus. Therefore, baptism is the door of the spiritual life. By it one is initiated into communion with the death of Jesus, and thereby original sin and all actual sins are taken away, together with all the punishment due to sin (see DS 1314/696). Moreover, God’s forgiveness of sin in baptism is most gracious and magnanimous, for the individual who is baptized need not outwardly confess his or her sins and need accept no personal responsibility to do penance for them (see S.t., 3, q. 68, aa. 5–6). The heavenly Father welcomes his prodigal children with joy (see Lk 15.11–24).
19. For a compact but rich historical study of baptismal theology, see Lorna Brockett, R.S.C.J., The Theology of Baptism, Theology Today Series, 25 (Hales Corners, Wis.: Clergy Book Service, 1971).
20. For theological reflections on baptism and entry into the Church in close harmony with the doctrine set out in the present question, see Louis Bouyer, Christian Initiation (New York: Macmillan, 1960), 60–97.
21. See Markus Barth, Ephesians: Introduction, Translation,and Commentary on Chapters 1–3, Anchor Bible, 34 (Garden City, N.Y.: Doubleday, 1974), 115–19 and 219–22; Eduard Lohse, Colossians and Philemon (Philadelphia: Fortress Press, 1971), 103–6 and 132–35.
22. St. John Chrysostom, Homilies on the Gospel of John, 1, 12.
23. If someone argues that the catechumen receives grace before baptism, I answer that perhaps grace is received before the rite of baptism is performed, but the sacrament begins earlier: when the catechumen, moved by grace, begins to move toward the rite. The rite only completes the long journey of souls seeking Jesus and of him in his Church seeking them.