Chapter 26: Lord's Day 26
Section 69. Q. 69: How does holy baptism remind you and assure you that Christ's one sacrifice on the cross is for you personally? A. In this way: Christ instituted this outward washing and with it gave the promise that, as surely as water washes away the dirt from the body, so certainly his blood and his Spirit wash away my soul's impurity, in other words, all my sins.
Section 70. Q. 70: What does it mean to be washed with Christ's blood and Spirit? A. To be washed with Christ's blood means that God, by grace, has forgiven my sins because of Christ's blood poured out for me in his sacrifice on the cross. To be washed with Christ's Spirit means that the Holy Spirit has renewed me and set me apart to be a member of Christ so that more and more I become dead to sin and increasingly live a holy and blameless life.
Section 71. Q. 71: Where does Christ promise that we are washed with his blood and Spirit as surely as we are washed with the water of baptism? A. In the institution of baptism where he says: 'Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.' And: 'Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.' This promise is repeated when Scripture calls baptism the washing of rebirth and the washing away of sins.
Section 72. 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.
Section 73. Q. 73: Why then does the Holy Spirit call baptism the washing of rebirth and the washing away of sins? A. God has good reasons for these words. He wants to teach us that the blood and Spirit of Christ wash away our sins just as water washes away dirt from the body. But more important, he wants to assure us, by this divine pledge and sign, that the washing away of our sins spiritually is as real as physical washing with water.
Section 74. Q. 74: Should infants also be baptized? A. Yes. Infants as well as adults are in God's covenant and are his people. They, no less than adults, are promised the forgiveness of sin through Christ's blood and the Holy Spirit who produces faith. Therefore, by baptism, the mark of the covenant, infants should be received into the Christian church and should be distinguished from the children of unbelievers. This was done in the Old Testament by circumcision, which was replaced in the New Testament by baptism.