What Is Baptism?

The 94th question of the Westminster Shorter Catechism asks, "What is baptism?"
It answers, "Baptism is a sacrament, wherein the washing with water in the name of the Father, and of the Son, and of the Holy Ghost, doth signify and seal our ingrafting into Christ, and partaking of the benefits of the covenant of grace, and our engagement to be the Lord’s." 

Baptism is a sacrament. What is a sacrament? 

“A sacrament is an holy ordinance instituted by Christ; wherein, by sensible signs, Christ, and the benefits of the new covenant, are represented, sealed, and applied to believers.” (WSC 92).

What is the an outward and sensible sign used in baptism? 

Washing with water (Acts 10:47, 22:16).

Is a certain amount of water needed for baptism to be valid? 

No, it simply needs to be washing with water. Baptism is legitimate whether it done by dipping, sprinkling, or pouring, although sprinkling and pouring are most expedient and especially appropriate (Is. 44:3, 52:15, Ezek. 36:25-27, 39:29, Acts 2:17-18, Heb. 9:19-22, 10:22).

What else must be added to the washing with water for it to be baptism? 

The word. The washing must be done into the name of the Father and of the Son and of the Holy Spirit, according to Christ’s institution (Matt. 28:18-20).

What is the significance of being baptized into the name of the Father and of the Son and of the Holy Spirit?
Jesus' reference to baptism in the Triune name in Matthew 28:19 should be understood in the context of the earlier reference to baptism in Matthew 3's account of his own baptism. When Jesus was baptized, the Father affirmed his identity as his Son and the Spirit descended upon him. Likewise, baptism symbolizes our union with the Son, adoption by the Father, and sanctification by the Holy Spirit. It is a sign and seal of our ingrafting into Christ (Rom. 6:3-5). Christ brings us to the Father and pours out upon us the Holy Spirit.

This form refers to being taken under the care, protection, and tuition of the triune God, receiving this salvation from the triune God, being adopted into the household of God, enlisted in the army of the Lord Jesus, and joined to the temple of the Spirit. In baptism, the Triune God receives us as his people, and we are initiated into the confession of the God the Father Almighty, Jesus Christ his only Son, and the Holy Spirit - one God, the same in substance, equal in power and glory. The baptismal formula is the most basic form of the Christian creed and covenant.

What kind of sacrament is baptism? How is it different from the Lord’s Supper? 

There are basically two kinds of sacraments: one, in which covenant members actively renew the covenant repeatedly throughout their life, and the other, in which people are visibly admitted into the covenant and its community. Passover (in the Old Testament) and the Lord’s Supper (in the New Testament) are the type which is repeatedly practiced, while circumcision (OT) and baptism (NT) are the type which is done once as a sign of your reception into the covenant and its community. Baptism is to be administered only once to a person, and even to infants, as a sign and seal of that definitive break with the old man and putting on the new man, of your ingrafting into Christ. The Lord’s Supper, as we will see, is to be administered often, to such as can examine themselves, to represent and exhibit Christ as spiritual nourishment to the soul.

What then is the inward and spiritual grace signified by baptism? 

It signifies and seals our ingrafting into Christ, and partaking of the benefits of the covenant of grace, and our engagement to be the Lord’s. (1) Our ingrafting into Christ is connected with baptism in Romans 6:3-5 and Galatians 3:27. (2) Our partaking of the benefits of the covenant of grace flows from our union with Christ (Gal. 3:27-29). Baptism thus symbolizes the washing away of sins (Acts 22:16), the washing of regeneration (Titus 3:5), and our membership in the body of Christ (1 Cor. 12:13). (3) Our engagement to be the Lord’s is also signified and sealed in baptism. This is our covenant obligation to be only and wholly his own, a holy people for his own possession. We receive him as our God in Christ and resolve to serve him according to his commandments as those bought with a price (Rom. 6:4, 13, Matt. 28:18-20). "But as for me and my house, we will serve the LORD" (Josh. 24:15b). 

Is this grace not given until a person is baptized? 

No, baptism is given to represent, confirm, and tangibly hold forth this grace to a person for the strengthening of their faith. The efficacy of baptism is not tied to that moment of time wherein it is administered. Abraham had the reality before he was given the sign of circumcision (Rom. 4:11). The same is obviously true of Cornelius and his household in Acts 10. We do not baptize pagans to convert them, but we baptize Christians, that is, members of the visible church (those who profess true religion and their children), to confirm the promises to them. John Calvin put it this way,

Let us take as proof of this, Cornelius the centurion, who, having already received forgiveness of sins and the visible graces of the Holy Spirit, was nevertheless baptized [Acts 10:48]. He did not seek an ampler forgiveness of sins through baptism, but a surer exercise of faith - indeed, increase of assurance from a pledge. Perhaps someone will object: why, then, did Ananias tell Paul to wash away his sins through baptism [Acts 22:16; cf. ch. 9: 17-18] if sins are not washed away by the power of baptism itself? I reply: we are said to receive, obtain, and acquire what, according as our faith is aware, is shown forth to us by the Lord, whether when he first testifies to it, or when he confirms more fully and more surely what has been attested. Ananias meant only this: "To be assured, Paul, that your sins are forgiven, be baptized. For the Lord promises forgiveness of sins in baptism; receive it, and be secure." Yet it is not my intention to weaken the force of baptism by not joining reality and truth to the sign, in so far as God works through outward means. But from this sacrament, as from all others, we obtain only as much as we receive in faith. If we lack faith, this will be evidence of our ungratefulness, which renders us chargeable before God, because we have not believed the promise given there. (Institutes of the Christian Religion, 4.15.15)

Can the grace promised in baptism be given to a person at a time subsequent to his baptism? 

Yes, it is also possible that a person comes to possess the promised grace at a time after he was baptized (as was the hope for Simon Magnus when Peter exhorted him to pray in Acts 9:20-23). Baptism is given to members of the visible church, and so not all are necessarily regenerate when they receive the sign. Often the Israelites were exhorted to become in reality what they were supposed to be by their circumcision (Deut. 10:16). When they converted in truth, they were not to receive the sign again, but to embrace the promises and obligations once sealed to them in their circumcision. The same with baptism. God makes baptism effectual to his elect, in his appointed time.

When and how should we use baptism?

We should use it throughout our lives, for its fruit and power reaches to the whole course of our life (it does not only apply to pre-baptismal sins). Baptism is designed to strengthen, direct, and distinguish you for the rest of your life. In the New Testament epistles, baptism is often appealed to in order to exhort or instruct Christians concerning themselves and how they ought to live (Col. 2:12, Eph. 4:5, Rom. 6:3ff, 1 Cor. 1:13, 12:13). This is how the Larger Catechism explains our continual use of baptism:

Q. 167. How is baptism to be improved by us? A. The needful but much neglected duty of improving our baptism, is to be performed by us all our life long, especially in the time of temptation, and when we are present at the administration of it to others; 

• by serious and thankful consideration of the nature of it, and of the ends for which Christ instituted it, the privileges and benefits conferred and sealed thereby, and our solemn vow made therein; 

• by being humbled for our sinful defilement, our falling short of, and walking contrary to, the grace of baptism, and our engagements; 

• by growing up to assurance of pardon of sin, and of all other blessings sealed to us in that sacrament; 

• by drawing strength from the death and resurrection of Christ, into whom we are baptized, for the mortifying of sin, and quickening of grace;  

• and by endeavoring to live by faith, to have our conversation in holiness and righteousness, as those that have therein given up their names to Christ; and to walk in brotherly love, as being baptized by the same Spirit into one body.