Heidelberg Catechism:Lord's Day 27

Question 72

Question: Is then the external baptism with water the washing away of sin itself?
Answer: Not at all: for the ^[1] blood of Jesus Christ only, and the Holy Ghost cleanse us from all ^[2] sin.

Question: Why then doth the Holy Ghost call baptism "the washing of regeneration," and "the washing away of sins"?
Answer: God speaks thus not without great cause, to-wit, not only thereby to teach us, that as the filth of the body is purged away by water, so our sins are ^[3] removed by the blood and Spirit of Jesus Christ; but especially that by ^[4] this divine pledge and sign he may assure us, that we are spiritually cleansed from our sins as really, as we are externally washed with water.

Question: Are infants also to be baptized?
Answer: Yes: for since they, as well as the adult, are included in the ^[5] covenant and ^[6] church of God; and since ^[7] redemption from sin by the blood of Christ, and the ^[8] Holy Ghost, the author of faith, is promised to them no less than to the adult; they must therefore by baptism, as a sign of the covenant, be also admitted into the christian church; and be distinguished ^[9] from the children of unbelievers as was done in the old covenant or testament by ^[10] circumcision, instead of which ^[11] baptism is instituted in the new covenant.