When God introduced circumcision, he called it “a sign of the covenant” between himself and Abraham (Genesis 17:11). The covenant existed before Abraham became circumcised (Genesis 12:1–3; 15:1–21; 17:1–8). This shows that it was on the basis of faith, not circumcision. Therefore, Abraham is the spiritual father of all people, whether circumcised (Jews) or uncircumcised (Gentiles), "who are of the faith of Abraham" (Romans 4:13–25).