That is why Abraham was to circumcise his children: they needed to know they were not free to choose their own gods. They were to receive the sign of the covenant to show them that they were part of the covenant people. They belonged to the one true God, and they were to submit to him in a covenant relationship.
The truly remarkable aspect of God’s command to Abraham was not the command to be circumcised, but the command to circumcise his children also. Circumcision was practiced quite widely among other peoples in the ancient Near East. However, in other religions it was usually a rite of purification associated with puberty, not something done in infancy. Yet when God chose Abraham, he didn’t choose just him; he chose his children as well. God is not only the God of Abraham, but also the God of Isaac and Jacob. That is why Abraham was to circumcise his children: they needed to know they were not free to choose their own gods. They were to receive the sign of the covenant to show them that they were part of the covenant people. They belonged to the one true God, and they were to submit to him in a covenant relationship.
Did circumcision save them? Absolutely not. Ishmael was circumcised on the same day as Abraham (Gen. 17:26), yet he showed no evidence of a heart renewed by grace. Although he bore the sign of the covenant, he was not ultimately part of God’s covenant people. As he grew up, he lived against (literally, “in the face of”) God’s covenant people (16:12), not in friendship with them. As Genesis 17:19–20 makes clear, although God’s blessing rested on Ishmael and his descendants, his covenant was with Isaac and his descendants. In a similar way, circumcision pointed Israel’s children to the one covenant God who alone could save them. If they trusted in him, like their father Abraham, they would find a refuge in him. But if they refused that God and rebelled against him, their very circumcision would testify against them. They too would be cut off from the presence of God, just as Ishmael was.
Circumcision and Baptism
The biblical background is why we baptize little children, for, as Peter declared on the day of Pentecost, the promised gift of the saving Holy Spirit is for our children as well as for us (Acts 2:39). Will baptism save your children? No. But it points them, as it points all of us, to Jesus Christ, whose cleansing blood is symbolized by the water. It points them to the need for a change that can only come from outside, for baptism, like circumcision, can be done to you only by someone else. Baptism also points them to the fact that they are part of God’s covenant people. They are not free to choose their gods as they please; they must surrender to the one true God or face the consequence of eternal separation from him in hell.
But baptism is more than that. Baptism is an act of faith in the promises of God. If baptism is your testimony that you chose God, then of course it makes no sense to baptize children. They have no clue what is happening to them, no more than Isaac understood why he was being circumcised. But if baptism is God’s promise that through Christ he is willing and able to accept your child, then it is a precious reminder to you and to your children of God’s grace and mercy. Abraham knew when he circumcised his children that the ritual was not enough: they too had to trust God in faith, just as he had. So also, when we baptize our children, we declare to them that faith in Christ is necessary for them too. In baptism, we quote back to God in prayer Peter’s declaration on the day of Pentecost, and we ask the only one who can save us and our children to act in their lives.