Few acts in the Christian life are so widely misunderstood or undervalued as baptism. To many outside the church, it may appear little more than a quaint tradition or cultural custom. Even among believers, it is often reduced to a mere symbol, a public declaration of faith without deeper significance. Yet the apostles and the early church did not treat baptism in such a casual way. They saw it as a moment of decisive divine action—a sacred threshold where the believer steps into new life. It is the event in which the Holy Spirit personally applies the benefits won by Christ’s death and resurrection. From Peter’s sermon on the day of Pentecost, where baptism is commanded as the gateway to forgiveness and the Spirit’s gift (Acts 2:38), to Paul’s letters that teach baptism as the instrument of regeneration and union with Christ (Rom 6:3–5; Titus 3:5), baptism emerges not as an optional ritual but as a God-ordained means of grace. 

This study seeks to recover this biblical and theological truth by first listening carefully to the voice of Scripture in its original languages and historical context, then by hearing the faithful witness of theologians across the ages—such as Irenaeus, Augustine, Aquinas, Calvin, Owen, and Bavinck—who labored to follow the same divine voice. In this way, we will understand what God truly does in baptism and why it remains essential for the Christian life.

Union with Christ in His Death and Resurrection

The apostle Paul writes in Rom 6:3–4: ”Or do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? Therefore, we were buried with him through baptism into death, in order that just as Christ was raised from the dead through the glory of the Father, so also we might walk in newness of life. The preposition εἰς (“into”) with the aorist passive ἐβαπτίσθημεν (“we were baptized”) signals a real, spiritual union with Christ. The believer is not merely symbolizing death and resurrection but is genuinely united with Christ in those events. The verb ἐβαπτίσθημεν, being in the passive voice, implies divine agency: God is the one acting through the baptism. As Cranfield notes, Paul does not allow for a merely symbolic reading here; rather, baptism is “a genuine participation in the death and resurrection of Christ” (Romans, ICC, 1:305).

Irenaeus affirmed this theological reality. In his Demonstration of the Apostolic Preaching, he writes: “For as we are lepers in sin, we are made clean by means of the sacred water and the invocation of the Lord, being spiritually regenerated as new-born babes” (3). For Irenaeus, baptism is no human initiative but divine cleansing and recreation in Christ. Aquinas, in Summa Theologiae III.66.1, refers to baptism as an “instrumental cause of grace,” underscoring that God works through the physical sign to apply spiritual reality. The union with Christ is accomplished not by water alone but by God acting through the Spirit.

Calvin, though rejecting any ex opere operato mechanism, nonetheless affirms God’s effective action in baptism. In Institutes 4.15.1, he writes, “Baptism is the sign of initiation by which we are admitted to the fellowship of the Church, that being engrafted into Christ we may be reckoned among the children of God.” John Owen writes, “The Lord Christ hath instituted baptism to be a pledge unto us of that blessed union and communion which we have with him” (The Doctrine of the Sacrament). The sign pledges not only God’s promise but his very presence through the Spirit. Herman Bavinck similarly insists: “Baptism is not a human work but a divine gift. God is the one who acts in baptism and through baptism grants what he promises” (Reformed Dogmatics, 4:531).

The Forgiveness of Sins

Peter’s command in Acts 2:38—“Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins”—centers on the phrase εἰς ἄφεσιν τῶν ἁμαρτιῶν. The preposition εἰς conveys more than association; it expresses purpose or result. Baptism is not only a witness to past forgiveness but is the divinely instituted means through which forgiveness is applied to the repentant believer in real time. As the New Revised Standard Version Updated Edition rightly renders it: “be baptized so that your sins may be forgiven.”

This language mirrors Jesus’ own words in the Upper Room: “This is my blood of the covenant, which is poured out for many for the forgiveness of sins” (Matt 26:28). The same phrase, εἰς ἄφεσιν τῶν ἁμαρτιῶν, is used in both instances. What Christ’s blood purchased, baptism in his name applies. It is not the external action alone that brings about forgiveness, but the Spirit working through the means of grace as it is received in faith.

This connection between the sign and the reality is deeply embedded in Calvin’s theology of the means of grace. Calvin affirms that the means of grace do not merely signify grace—they also confer what they signify, when received by faith. He writes:“Whenever the Lord gives us such symbols, he also works inwardly by his Spirit, so that the symbol is not without effect. Therefore, if we rightly receive this means of grace in faith, we surely feel the effectiveness of Christ’s death and the power of his resurrection” (Institutes 4.14.17). Here, Calvin upholds that the sign is not empty; it is divinely ordained to accomplish its purpose in the faithful recipient. He resists both the Roman Catholic ex opere operato view and the Anabaptist tendency to reduce baptism to a mere symbol. For Calvin, the sign is effective because of God’s promise and presence, not because of the rite alone.

This is seen clearly in his Commentary on Acts 2:38, where Calvin writes: “Forgiveness of sins and the gift of the Holy Spirit are annexed to baptism; not because baptism confers them by itself, but because the Lord, by this mark, declares his will to bestow them on believers.”

Baptism, then, is the divinely chosen point of application for God’s promise. It is not effective apart from faith, but it is not meaningless either. Calvin holds this tension with clarity. Again, in Institutes 4.15.2, he writes: “Although baptism is administered with water, it is not to be separated from the blood of Christ and the Spirit of God… the Lord offers in baptism the true washing of sins and the new life of the Spirit.”

The verb ἀπόλουσαι (“wash away”) in Acts 22:16 is aorist middle imperative, suggesting participation in the act, yet not its origin. The one baptized is not the actor; God is. The middle voice points to what God does to the believer through the invocation of Christ’s name (ἐπικαλεσάμενος τὸ ὄνομα αὐτοῦ). Baptism is thus the means of grace and the moment of divine cleansing for the one who calls on Christ in faith. As in Joel 2:32 and Romans 10:13, “everyone who calls on the name of the Lord shall be saved.”

Calvin elaborates this further in his Commentary on Titus 3:5, which speaks of “the washing of regeneration and renewal of the Holy Spirit” (διὰ λουτροῦ παλιγγενεσίας καὶ ἀνακαινώσεως πνεύματος ἁγίου). He writes: “Paul means that baptism is an outward sign by which the washing away of sins is confirmed to us. It is not a bare figure, but an effectual seal by which the Spirit truly works to cleanse and renew.” Calvin sees baptism as a real instrument of grace, joined to Christ by the Spirit through faith. The outward sign is joined to the inward reality. Again, from the Institutes: “The Lord… does not deceive us with empty promises. Therefore, it is necessary that the reality be joined to the sign, otherwise the means of grace would be a deception” (Institutes 4.14.14). This view echoes Augustine’s famous dictum, Accedit verbum ad elementum, et fit means of graceum—“Add the word to the element and you have a means of grace.” 

Calvin honors that patristic tradition. Yet he guards against any idea that forgiveness is tied to baptism regardless of faith. He distinguishes carefully: “We must hold that the efficacy of the means of grace resides in the Spirit of God, and that it is not tied to the outward element in such a way that the fruit is always received by all indiscriminately” (Institutes 4.14.15). In this way, Calvin’s theology aligns with the biblical testimony. The forgiveness of sins is not the work of water, but of God through the Spirit of Christ. Yet baptism is not a bare sign—it is the moment when, by God’s appointment, the cleansing blood of Christ is applied to the one who believes. Augustine is right to declare, “The water touches the body, and cleanses the heart” (Sermon 227). And Calvin brings clarity to both: “We put on Christ truly in baptism, and we are truly washed by his blood” (Institutes 4.15.5). As Bavinck sums up, “Baptism seals to us the washing away of sins by the blood and Spirit of Christ” (RD 4:534). It is no fiction. It is a real means of grace for all who believe.

The Gift of the Holy Spirit

Acts 2:38 again links baptism and the Holy Spirit: “And you will receive the gift of the Holy Spirit.” The coordination of μετανοήσατε (“repent”) and βαπτισθήτω (“let each be baptized”) with λήμψεσθε (“you will receive”) ties the actions together in divine sequence. In Titus 3:5, Paul writes that God saved us “by the washing of regeneration and renewal of the Holy Spirit.” The term λουτροῦ παλιγγενεσίας refers not only to ritual washing but to a Spirit-empowered new birth. The genitive construction τοῦ ἁγίου πνεύματος makes the Spirit the agent of this renewal.

Paul’s teaching in Titus 3:5 deepens the theological foundation: God “saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit” (διὰ λουτροῦ παλιγγενεσίας καὶ ἀνακαινώσεως πνεύματος ἁγίου). The genitive construction πνεύματος ἁγίου is best taken as subjective genitive, identifying the Spirit as the agent who brings about this rebirth. The term λουτρόν, “washing,” denotes more than symbolic cleansing. It evokes the concrete rite of baptism, now invested with new meaning: a Spirit-empowered new creation (cf. 2 Cor 5:17). The word παλιγγενεσία, “regeneration,” occurs only here and in Matthew 19:28. In both cases, it refers to a divinely wrought new beginning. The preposition διὰ indicates the means by which salvation is effected, aligning closely with Paul’s logic in Romans 6:4 that through baptism, we are “buried with [Christ]… in order that… we too might walk in newness of life.”

The Spirit is not only the agent of this regeneration, but also the one who indwells. As Paul writes in 1 Corinthians 12:13, “For in one Spirit we were all baptized into one body… and all were made to drink of one Spirit.” The dual metaphors of baptism and drinking emphasize both incorporation into the church and participation in the Spirit. The phrase ἐν ἑνὶ πνεύματι ἐβαπτίσθημεν indicates that the Spirit is both the environment and the active force by which believers are united to Christ. This reception is not external or superficial but essential to the Christian life (cf. Rom 8:9: “Anyone who does not have the Spirit of Christ does not belong to him”).

Cyril of Jerusalem, in his Mystagogical Catecheses 2.4, affirms the unity of baptism and the Spirit’s work: “At that same moment you were made partakers of the Holy Spirit.” For Cyril, the Spirit is not an optional addition to Christian initiation but an immediate gift conferred in baptism. This reflects the early church’s conviction that baptism was not a bare sign but a Spirit-filled moment of transformation. Similarly, Ambrose speaks of baptism as the time when “the Spirit is poured upon you” (De Mysteriis 7.36). These are not general associations but direct assertions of divine action mediated through the means of grace.

Aquinas, with theological precision, writes: “The Holy Spirit is given in baptism as the cause of spiritual rebirth” (ST III.69.1). He sees baptism as instrumental, the Spirit as efficient, and faith as the necessary disposition. Baptism does not work by the power of the rite itself (ex opere operato in isolation), but by the Spirit working through the rite according to the intention of God and the disposition of the recipient.

Calvin stands in close agreement. He affirms that “as often as we are baptized, we are washed and purged for the forgiveness of sins… the Spirit is the author and minister of this grace” (Institutes 4.15.5). Yet Calvin insists that the Spirit is not automatically bound to the water. Rather, the Spirit truly works through baptism in those who receive by faith. “We must beware,” he warns, “lest we separate what the Lord has joined together” (Institutes 4.15.16). This pairing—Spirit and water, promise and sign—is essential to a biblical and Reformed theology of baptism.

Thus, the gift of the Holy Spirit in baptism is neither magical nor empty. It is the fulfillment of divine promise, the presence of the divine Person, and the means by which believers are united to Christ and his body. Baptism, joined with faith, becomes the threshold of new creation (Gal 3:27; Eph 4:4–6). The Spirit does not merely hover over the waters. He enters, renews, and indwells those who are united to Christ in the name of the Father, and of the Son, and of the Holy Spirit.

Conclusion

The New Testament clearly presents baptism as the work of God rather than the achievement of human effort. In this sacred act, God himself unites believers with Christ in his death and resurrection (Romans 6:3–5), forgives their sins (Acts 2:38), bestows the Holy Spirit (Titus 3:5), and incorporates them into the fellowship of the church, the communion of saints (1 Corinthians 12:13). This was never a peripheral or optional teaching in the apostolic age or among the church fathers. On the contrary, it stood at the heart of Christian identity and mission. 

The great theologians across the centuries—from the early fathers to Aquinas, Calvin, Owen, and Bavinck—all testify that baptism is a true means of grace through which God applies the benefits of Christ’s work to the believer. Calvin’s profound insight that the sign accomplishes what it signifies captures this well: baptism is not a mere symbol but the Spirit-filled seal of God’s saving work (Institutes 4.15.2). Faith receives what grace alone provides, and baptism is the visible mark of that inward transformation. To grasp baptism rightly is to enter into profound joy—rejoicing not in human effort but in the glorious reality that God, through his Son and by his Spirit, accomplishes our new birth, cleansing, and adoption into his family. This is baptism’s true power and glory.