Upon reading Genesis 17:10, many have come to this conclusion. The verse states, “Every man child among you shall be circumcised.” This was an outward physical sign of the covenant between God and Abraham, including his physical seed, to whom the covenant applied—the nation of Israel. Circumcision was specifically a token (vs. 11)—a sign—of that covenant with Abraham and his descendants, rather than part of the civil law or Levitical rituals later established through Moses.
However, under the New Covenant, God is selecting and calling out from the world a spiritual nation of Israel—His Church. Upon baptism and conversion, these few are led by the power of His Holy Spirit. The apostle Paul explains: “For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit” (Rom. 2:28-29).
Through God’s Spirit, one becomes “circumcised in the heart.” No longer is physical circumcision the sign for one who follows and obeys God—spiritual circumcision is! The custom of circumcision was merely a forerunner—a physical parallel—of what God really wanted and intended for all mankind: circumcision of the heart (Jer. 4:4; Deut. 10:16; 30:6).
Upon conversion, one becomes spiritually “circumcised.” Paul further explains to the Colossians, “And you are complete in Him [Christ], which is the Head of all principality and power: In whom also you are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ” (2:10-11).
For this reason, the apostles in the New Testament, recognizing that circumcision applied to the covenant with the seed of Abraham, never made this mandatory upon Gentiles called into the Church (see Acts 15:24, 28). Neither was it mandatory upon Christians, in general, being called under the New Covenant, as shown in Romans 2:28-29 quoted above.
Today, most doctors and physicians do recommend circumcision for health reasons and cleanliness. But this is solely based on health, rather than religious reasons.