Romans 4:11-14

Circumcision was a sign that Abraham already had faith and that God had already accepted him and declared him to be righteous—even before he was circumcised. So Abraham is the spiritual father of those who have faith but have not been circumcised. They are counted as righteous because of their faith. And Abraham is also the spiritual father of those who have been circumcised, but only if they have the same kind of faith Abraham had before he was circumcised. Clearly, God’s promise to give the whole earth to Abraham and his descendants was based not on his obedience to God’s law, but on a right relationship with God that comes by faith. If God’s promise is only for those who obey the law, then faith is not necessary and the promise is pointless.