But Zipporah took a flint knife and circumcised her son. Taking the skin, she touched Moses’ feet with it and said to him, “You are a bridegroom of blood to me.”
A person is a Jew only if he is a Jew inside; true circumcision is done in the heart by the Spirit, not by the written law. Such a person gets praise from God rather than from people.
Abraham was circumcised to show that he was right with God through faith before he was circumcised. So Abraham is the father of all those who believe but are not circumcised; he is the father of all believers who are accepted as being right with God.
Also in Christ you had a different kind of circumcision, a circumcision not done by hands. It was through Christ’s circumcision, that is, his death, that you were made free from the power of your sinful self.