Galatians addresses the sensitive and complex issue of the role Old Testament Law plays in salvation, specifically regarding circumcision. Paul's main goal in his letter to the Galatians is to defend salvation by faith in Jesus, not by works of the Law. But in order to follow his argument and understand the good news he is sharing, we must grasp the true purpose of circumcision. This sign was given to point to Abraham's future descendent who would be a blessing to all nations. That sign was fulfilled in Jesus. Therefore, faith in Jesus is the fulfillment of the command to be circumcised.