Explaining Baptism in Children's Language
It is a blessing to see a child at this age inquiring of such godly things. Wording this answer would vary from child to child as all are at different stages of growth. As a parent, you know your child best and need to select the appropriate words that will assist them to understand the teaching of Scripture.
In addition, I believe children should memorize and have a basic understanding of the First Catechism and/or Westminster Shorter Catechism with their biblical foundations at a very young age. This would assist greatly with them understanding the doctrines of baptism, Christ, salvation, etc.
However, there are some things that need to be taught "continually" (Deut. 6:1-9; Rom. 10:17) for improving upon one's baptism. In basic, elementary terms these are:
1. A covenant is a legal agreement between two or more parties (ex. Gen. 17). See: Teaching Covenant.
2. Each covenant normally has a sign: Adam - tree of life (Gen. 2:9); Noah - rainbow (Gen 9:13); Abraham - circumcision (Gen. 17); Moses - tables of stone (Ex. 24:12); Christ - baptism (Matt. 28:18-20; Col. 2:11-12; see Infant Baptism).
3. The sign and seal of baptism in the New Testament demonstrate they belong to Jesus, not the world (Acts 2:39; 1 Cor. 7:14). By baptism they are members of God's covenant (Matt. 19:14; Mark 10:13-16; Luke 18:16). It is a covenant of love (Deut 7:6-13; 1 Sam. 18:1-3; Eph. 5:31-32). God loves them (Psa. 103:17; Matt. 18:4-6; Eph. 6:1-4).
4. As members of the covenant, they are called to believe and repent (Jer. 4:4; Acts 17:30; 1 John 3:23; cf. Eph. 2:8-10; 2 Tim. 2:24-26).
5. All the promises and warnings of the Bible are for them (Lev. 26; Deut. 28; Psa. 1:1-2; 119:1; 1 Cor. 11:28-34; Gal. 3:10-14; Heb. 6:4-6; 10:26-31; 2 Pet. 1:3-11), and in the covenant there are both privileges and responsibilities.
6. As they look back to their baptism (Westminster Confession of Faith Chapter 28.6), what happened outwardly in the action of washing in baptism must also be what happens to them inwardly so they will be fit for eternal life with God. They need to be washed by Jesus' blood (Rom. 4:11; 6:4-7; 1 Pet. 3:21).
7. The only way this may happen is to believe in the birth, life, death, and resurrection of Jesus (Acts 4:12; Rom. 10:9-10, 17). One may be enabled to believe this divine truth only by grace alone (John 1:13; 3:1-8; 6:44, 65; Rom. 9:16).
8. Tell them the story of Jesus (Acts 2:14-41; 1 Cor. 15:1-4). Tell them your own story of salvation (1 Pet. 3:15).
9. True salvation, by grace alone, enables us to: both desire to and to actually obey Christ (Rom. 8:5-8; 1 Cor. 2:14); to improve upon our baptism (Westminster Larger Catechism Question 167); to be loyal to Christ and his way(s) (1 Pet. 2:9-12; 2 Pet. 1:3-4; 1 Tim. 1:14; 1 John 3:24); realize only Jesus lived a perfect life (2 Cor. 5:21; Heb. 4:15; 1 Pet. 2:22; 1 John 3:5; cf. I John 1:9).
The Westminster Shorter Catechism:
Q. 94. What is baptism?
A. 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.
Q. 95. To whom is baptism to be administered?
A. Baptism is not to be administered to any that are out of the visible church, till they profess their faith in Christ, and obedience to him; but the infants of such as are members of the visible church are to be baptized.
The Larger Catechism:
Question 165: What is Baptism?
Answer: Baptism is a sacrament of the New Testament, wherein Christ has ordained the washing with water in the name of the Father, and of the Son, and of the Holy Ghost, to be a sign and seal of ingrafting into himself, of remission of sins by his blood, and regeneration by his Spirit; of adoption, and resurrection unto everlasting life; and whereby the parties baptized are solemnly admitted into the visible church, and enter into an open and professed engagement to be wholly and only the Lord's.
Question 166: Unto whom is Baptism to be administered?
Answer: Baptism is not to be administered to any that are out of the visible church, and so strangers from the covenant of promise, till they profess their faith in Christ, and obedience to him, but infants descending from parents, either both, or but one of them, professing faith in Christ, and obedience to him, are in that respect within the covenant, and to be baptized.
Question 167: How is our Baptism to be improved by us?
Answer: 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.
Confession of Faith:
I. Baptism is a sacrament of the New Testament, ordained by Jesus Christ, not only for the solemn admission of the party baptized into the visible Church; but also to be unto him a sign and seal of the covenant of grace, of his ingrafting into Christ, of regeneration, of remission of sins, and of his giving up unto God, through Jesus Christ, to walk in the newness of life. Which sacrament is, by Christ's own appointment, to be continued in His Church until the end of the world.
II. The outward element to be used in this sacrament is water, wherewith the party is to be baptized, in the name of the Father, and of the Son, and of the Holy Ghost, by a minister of the Gospel, lawfully called thereunto.
III. Dipping of the person into the water is not necessary; but Baptism is rightly administered by pouring, or sprinkling water upon the person.
IV. Not only those that do actually profess faith in and obedience unto Christ, but also the infants of one, or both, believing parents, are to be baptized.
V. Although it is a great sin to contemn or neglect this ordinance, yet grace and salvation are not so inseparably annexed unto it, as that no person can be regenerated, or saved, without it: or, that all that are baptized are undoubtedly regenerated.
VI. The efficacy of Baptism is not tied to that moment of time wherein it is administered; yet, notwithstanding, by the right use of this ordinance, the grace promised is not only offered, but really exhibited, and conferred, by the Holy Ghost, to such (whether of age or infants) as that grace belongs unto, according to the counsel of God's own will, in His appointed time.
VII. The sacrament of Baptism is but once to be administered unto any person.
Although there is much more to learn, these are the basics that should be "continually" emphasized.
Related Links:Infant Baptism, an audio by Richard Pratt.
JEREMIAH 31: Infant Baptism in the New Covenant, by Richard Pratt.
Is Infant Baptism Scriptural?, by John Murray.
A Conversation Concerning Infant Baptism, by Jeff Rojan.
Infant Baptism: How My Mind Has Changed, by Dennis Johnson.
Why Do We Baptize our Children?, a video by Richard Pratt, for purchase at: IIIM eStore.
Dr. Joseph R. Nally, Jr., D.D., M.Div. is the Theological Editor at Third Millennium Ministries (IIIM).