Heidelberg Catechism Lord's Day 27
Q. #72 Does this outward washing with water itself wash away sins?
A. No, only Jesus Christ’s blood and the Holy Spirit cleanse us from all sins.1
1 Matt. 3:11; 1 Pet. 3:21; 1 John 1:7
Q. #73 Why then does the Holy Spirit call baptism the water of rebirth and the washing away of sins?
A. God has good reason for these words. To begin with, God wants to teach us that the blood and Spirit of Christ take away our sins
just as water removes dirt from the body.1 But more important, God wants to assure us, by this divine pledge and sign, that we are as truly washed of our sins spiritually as our bodies are washed with water physically.2
1 1 Cor. 6:11; Rev. 1:5; 7:14
2 Acts 2:38; Rom. 6:3-4; Gal. 3:27
Q. #74 Should infants also be baptized?
A. Yes. Infants as well as adults are included in God’s covenant and people,1 and they, no less than adults, are promised deliverance from sin through Christ’s blood and the Holy Spirit who produces faith.2 Therefore, by baptism, the sign of the covenant, they too should be incorporated into the Christian church and distinguished from the children of unbelievers.3 This was done in the Old Testament by circumcision,4 which was replaced in the New Testament by baptism.5
1 Gen. 17:7; Matt. 19:14
2 Isa. 44:1-3; Acts 2:38-39; 16:31
3 Acts 10:47; 1 Cor. 7:14
4 Gen. 17:9-14
5 Col. 2:11-13