For circumcision verily profiteth, if thou keep the law: but if thou be a breaker of the law, thy circumcision is made uncircumcision. Therefore if the uncircumcision keep the righteousness of the law, shall not his uncircumcision be counted for circumcision? And shall not uncircumcision which is by nature, if it fulfil the law, judge thee, who by the letter and circumcision dost transgress the law? 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, and not in the letter; whose praise is not of men, but of God. Romans 2:25-29

The grace of God through Jesus Christ is a beautiful and mysterious thing, many have a hard time understanding it by Gods grace we are saved and not by our own works. Consider what the Apostle Paul said  “For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast” (Ephesians 2:8-9) We are saved by Gods grace through our faith in Jesus Christ, its not by our works, its by Christ works that he completed on the cross

So many people have a hard time accepting and understanding this concept of Gods grace, so the topic of circumcision would routinely come up to challenge Gods grace. Now you can substitute circumcision and insert and work that you believe will save you, and while this was a popular debate back in the 1rst century, this same topic is still being debated today. 

The confusion begins as God required circumcision , which is a sign of the Abrahamic covenant, to be part of the Mosaic Covenant. (Leviticus 12:2-3) As the Apostle Paul is saying here “if you are a breaker of the Law (sinner) your circumcision has become uncircumcision” The Jews were under the impression the act of circumcision saves you and makes you righteous being a child of Abraham. However Paul is revealing we are all sinners (Romans 3:23), and nobody can keep the law (Galatians 3:11) therefor when it comes to salvation, the act of circumcision will not save you, only faith in Christ can save you

Many people today still have this same attitude, if I do this and that, I will be saved. But the reality is, all our good works are filthy rags to God (Isaiah 64:6) we are only saved by the works of Jesus Christ. Then the Apostle Paul teaches us about the circumcision of the heart (Colossians 2:11) As Jesus said “ You must be Born Again or you will not see the Kingdom of Heaven” (John 3:3) We must be regenerated by the Holy Spirit, we need a new heart and mind of Christ.

 As Paul says here “He who is a Jew (Child of God) who is one inwardly , and circumcision is of the heart,  in the Spirit, not the letter (Law) The only way to salvation is Jesus Christ (John 14:6, Acts 4:12) and not ourselves. The Law is written on our hearts, and we live for Christ because we love and obey him. Some people try to use this scripture to say the Jews have been replaced, that’s not the point of this teaching. Point is we are all Children of God (Jew and Gentile) through faith in Christ and not of ourselves, Amen