Paul wrote in 1 Corinthians 10:1-2, “For I want you to know, brothers, that our fathers were all under the cloud, and all passed through the sea, and all were baptized into Moses in the cloud and in the sea.” The cloud refers to the pillar of cloud by day and the pillar of fire by night in which God manifested His presence by the Spirit among the Israelites (Isa. 63:9-14). The sea, of course, refers to the Red Sea, and particularly to the miraculous parting of the waters so that Israel could pass safely through the sea when fleeing from Egypt. The Spirit-cloud and the sea together comprised the fathers’ baptism into Moses, a sign of their separation from Egypt and their union with God in the Mosaic Covenant. Of course, this baptism was not continued as the covenant sign under the Mosaic Administration. The perpetual sign of the covenant under Moses from generation to generation was circumcision. Circumcision embodied the same sacramental reality as Israel’s baptism in the cloud and in the sea. When the children of Israel entered the Promised Land after forty years of wilderness wandering, none of them had been circumcised, because their parents had not been diligent to keep covenant with God. So, we read in Joshua 5 that all who were born in the wilderness were circumcised on that day. “And the LORD said to Joshua, ‘Today I have rolled away the reproach of Egypt from you.’” So circumcision, like the baptism in the Spirit-cloud and sea, conveys the benefit of a cleansing of the filth of Egypt, the filth of idolatry and bondage to sin.
What is remarkable here is the description of baptism as “in the cloud and in the sea,” in other words Spirit and water. Paul does not conceive of baptism as a merely outward sign, namely water, which can be divorced from the reality signified, namely the Spirit. So with no explanation Paul says, just two chapters later, “For in one Spirit we were all baptized into one body” (12:13). This biblical understanding of baptism is captured in WCF 27.2-e Of the Sacraments, “There is, in every sacrament, a spiritual relation, or sacramental union, between the sign and the things signified: whence it comes to pass, that the names and effects of the one are attributed to the other. The grace which is exhibited in or by the sacraments rightly used, is not conferred by any power in them; neither doth the efficacy of a sacrament depend upon the piety or intention of him that doth administer it: but upon the work of the Spirit, and the word of institution, which contains, together with a precept authorizing the use thereof, a promise of benefit to worthy receivers.”
So the power of the sacrament is not any magical properties in the water, it is the power of the Holy Spirit of God applying the Word of God, of the Father, of the Son, and of the Holy Spirit, as “a promise of benefit to worthy receivers.” Just like the preaching of the gospel to unbelievers may not have any immediately visible fruit, but may come to fruition some time later, so the confession goes on to say, “The efficacy of Baptism is not tied to that moment of time wherein it is administered.” Nevertheless, there is an efficacy or power. It is the power of the Holy Spirit and of the promise of the gospel. It is not a guarantee of the final salvation of all who are baptized. After speaking of the Baptism of the fathers in the cloud and in the sea, Paul goes on to say, “Nevetheless, with most of them God was not pleased, for they were overthrown in the wilderness” (1 Cor. 10:5). Then comes his warning to us not to be like them. “The promise of benefit,” to borrow the words of the Confession, is to “worthy receivers.” That means to those who embrace Jesus Christ by faith. This does not mean that Baptism has no covenantal efficacy for those who grow up to reject Jesus Christ. The Spirit always accompanies the Word and Sacraments when rightly administered. But when the covenant is rejected, the Spirit is outraged and the covenant curses, rather than the covenant blessings, are visited on the baptized. Michael Horton summarizes the biblical teaching well in these words: “Apart from faith, outward circumcision (and baptism in the New Covenant) is the sign and seal of judgment leading to death: a final cutting off of the whole person (excommunication). Hence, the severe warnings about falling away, especially in Hebrews 4, 6, and 10.”
Exhortation to Parents:
Parents, this truth about the power of the Word and Spirit through Baptism is sobering. Let me follow them with these words of encouragement from Hebrews, “Though we speak in this way, yet in your case, beloved, we feel sure of better things—things that belong to salvation. For God is not unjust so as to overlook your work and the love that you have shown for His name in serving the saints, as you still do. And we desire each one of you to show the same earnestness to have the full assurance of hope until the end, so that you may not be sluggish, but imitators of those who through faith and patience inherit the promises” (Heb. 6:9-12). Parents, you bring your child to the baptismal font in the light of the gracious character of the New Covenant in Christ. May God’s covenantal promise to you and to your children encourage you to strive by every means of God’s appointment to bring her up in the nurture and admonition of the Lord. We urge you to teach her diligently the whole counsel of God from the Scriptures. We commend the catechisms of our church as aids in that instruction. We encourage memorization and thorough instruction in both Scripture and the catechisms as faithful summaries of the Scriptures. Do not cease to pray for her and with her to know God as her God and Redeemer. And model for her in all of your conduct and conversation that wholehearted love for God and neighbor which is the sum and substance of God’s moral law.
A Baptismal Prayer
Our gracious God and Father, we bless Your name for the grace of the outward sign of Baptism which bears witness to us of Your promise which is “Yes!” and “Amen!” in Christ Jesus our Lord. We bless Your name for the grace of the Holy Spirit working inwardly through the Word and sacrament upon all to whom this grace belongs, according to Your own counsel and in Your appointed time. Bless this sacrament, we pray You, to this covenant child, that she may know You as her God and her Redeemer, and confess from her heart that Jesus is Lord. We bless You for regarding her as holy for the sake of these Your children, her parents. Through Christ we pray. Amen.
 Michael Horton, The Christian Faith: A Systematic Theology for Pilgrims on the Way (Grand Rapids, MI: Zondervan, 2011), 791.