In his gospel, John said that it is of Christ’s fullness that we not only receive grace, but grace upon grace. This abounding grace appears in God’s words to Abraham that he would not only be God to him; but He would also be God to Abraham’s children after him in their generations. The sign of that covenant promise was circumcision, which was given to Abraham’s children as much as it was given to Abraham. Likewise, in the new covenant, God has promised that His covenant is for us and our children, and likewise the covenant sign, which is baptism.