What follows is taken from a larger essay, “A Contemporary Reformed Defense of Infant Baptism:”
What is the Connection Between Circumcision and Baptism?
The connection between baptism and circumcision is quite clear in Colossians 2:11–12. The connection is not direct, but indirect and the point of contact between them is Christ and baptism is the sign and seal of that circumcision. In v.11 Paul says “in him [i.e. in Christ] you were also circumcised with the circumcision done by Christ” and in v.12 he says exactly how it is that we were circumcised in and by Christ: “having been buried with him in baptism and raised with him through your faith….” For Paul, in the New covenant, our union with Christ is our circumcision. In baptism, we are identified with Christ’s baptism/circumcision, as it were, on the cross. Neither baptism nor circumcision effects this union (ex opere operato), rather God the Spirit unites us to Christ, makes us alive and gives us faith.
The point not to be missed is that, in Paul’s mind, baptism and circumcision are both signs and seals of Christ’s baptism/circumcision on the cross for us. By faith, we are united to Christ’s circumcision and by union with Christ we become participants in his circumcision/baptism. Because circumcision pointed forward to Christ’s death and baptism looks back to Christ’s death, they are closely linked in Paul’s mind and almost interchangeable. Paul’s point here is to teach us about our union with Christ, but along the way we see how he thinks about baptism and circumcision and his thinking should inform ours.
One of the reasons that Paul so strongly opposed the imposition of circumcision upon Christians by the Judaizers is that, by faith, we have already been circumcised in Christ, of which baptism is the sign and seal. We were already identified as belonging to God and we have undergone the curse in Christ. So actual physical circumcision is, in the new covenant, unnecessary. Paul tells those who wish to circumcise themselves, to go the whole way and emasculate themselves.
Acts 2:38, 39 also links circumcision and baptism. In Acts 2:38 the Apostle Peter calls for repentance, faith in Christ and baptism by Jews who are hearing his preaching. In v.39 he gives the reason for this action: “the promise is to you and to your children, and all who are far off….” The Apostle Peter consciously uses the same formula in his preaching as the LORD himself used when he instituted the sign of circumcision in Genesis 17, which the Jews listening understood precisely.
What are the Relations Between Faith and Circumcision?
Romans 4:1–8, 13–25 teaches that Abraham was justified by grace alone, through faith alone and not by works and yet God required that Abraham take the sign (mark) of circumcision. Romans 4:11 says that circumcision was a sign and a seal of “the righteousness that he (Abraham) had by faith while he was still uncircumcised.” Circumcision was a sign of God’s covenantal relationship to Abraham and to Abraham’s children, all who believe in Christ. The meaning of circumcision was spiritual and not just outward. Circumcision as a sign of faith and entrance into the covenant people as a member was also applied to children.
What is the Relationship Between Faith and Baptism?
Acts 2:38, 39 says,
Repent and be baptized every one of you, in the name of Jesus Christ, so that your sins may be forgiven and you will receive the gift of the Holy Spirit. The promise is for you and for your children and for many who are-for all whom the Lord our God will call.
For adult converts, baptism is a sign of what Christ has done for them, forgiven them and washed them. Adult converts are baptized in the name of Jesus Christ. Forgiveness is through faith in Christ. Baptism is a sign of our new standing with God through faith. Notice, v.39 “The promise (of salvation to those who believe) is for you and for your children.”
Our faith is in the Christ who died for us. Like circumcision, baptism is a sign of being united to him in his death by faith. Peter says that the flood waters of Noah symbolize baptism, because baptism is a sign of dying to sin, the washing away of sin by Christ’s blood, and living by faith in Christ.
Everyone, (adults and children), who has been baptized must be united by faith to Christ for salvation. Unbaptized, adult converts, profess their faith before baptism. Children of believers who received the sign in infancy profess their faith as soon as they are able. Both are responsible before God to be faithful to the grace represented by the sign and seal they have received.
That, however, has always been true. No one has ever been accepted by God except by grace alone, through faith alone, in Christ alone. Christ and his benefits were illustrated by a forward-looking sign and seal under Abraham, Moses, David, and the prophets. In Christ the fulfillment has come and we no longer have need of the bloody illustration. It has been fulfilled and replaced by an unbloody, sign and seal that looks back to Christ’s finished work. The promise that God made to Abraham, however, is explicitly repeated in the New Covenant by the Apostle Peter. Therefore that promise (the promise is to you and to your children) does not belong to the illustration (Abraham, Moses et al) only. Rather, the promise is also part of the covenant of grace. The administration of the promise included adults and children under Abraham and, according to Peter, it includes them in the New Covenant as well. This is why the Apostle Paul links circumcision and baptism via Christ’s death.