We have been saying that Abraham’s faith was credited to him as righteousness. 10 Under what circumstances was it credited? Was it after he was circumcised, or before? It was not after, but before! 11 And he received circumcision as a sign, a seal of the righteousness that he had by faith while he was still uncircumcised. So then, he is the father of all who believe but have not been circumcised, in order that righteousness might be credited to them. 12 And he is then also the father of the circumcised who not only are circumcised but who also follow in the footsteps of the faith that our father Abraham had before he was circumcised.
Circumcision was a sign of the covenant God made with Israel through Abraham. When Abraham's long awaited son Issac was born, God commanded all Jewish boys and men to be circumcised before becoming eight days old. Genesis 17 describes this covenant,
Then God said to Abraham, “As for you, you must keep my covenant, you and your descendants after you for the generations to come. 10 This is my covenant with you and your descendants after you, the covenant you are to keep: Every male among you shall be circumcised. 11 You are to undergo circumcision, and it will be the sign of the covenant between me and you.
Paul's point in today's lesson is that Abraham had faith that was credited to him as righteousness before he was circumcised. Logically then, merely being circumcised does not constitute faith, but is a sign of covenant God made with Israel to be trusted in by faith. In Genesis 15:6 when God described the blessing he would give to Abraham and his descendants the bible says, "Abram believed in God and it was credited to him as righteousness."
Paul uses this example to tell the Jews that even though the Gentiles were not circumcised, they could come to God by faith just as Abraham did. This example is similar to baptism in the Christian community. Baptism is a sign of the new covenant God has made with us in Jesus. We are saved by faith, and baptism in water seals this covenant. It is an outward sign of the transformation saving faith in Christ has brought us. Infants are baptized as a sign that they are children of the new covenant God has made with us through Jesus.
In Baptism, God chooses us to be his children, just as God chose Abraham. Abraham believed in the promises God made to him. When babies who are baptized grow up, they come to believe in the promises that God has made to them. Of course just like in the passage there are some who come to believe in Jesus, and then are baptized.
As a pastor I am doing more and more adult baptisms now than ever before. As people come to our church from other cultures where they were not brought up in a Christian church, they are baptized as they come to faith in Christ. But as Paul says, whether someone is baptized as a baby and grows in their understanding of faith, or they come to faith and then are baptized, the key thing is they are made right with God by faith. Baptism is a sign of the covenant, as water is a reminder that our sins have been washed in Jesus' name.
And if you are baptized you should remember your baptism often in practical and tangible ways. The water of baptism reminds you of what God has done for you. It is a reminder that He has given you the Holy Spirit to assure you that you are a child of God. Thank God for these signs God has given us to remind us with earthly things the heavenly realities we have been given.