Christians are the true circumcised people of God. In Romans 2:28-29, Paul reveals that true circumcision is a matter of the heart, not the flesh, and that true Judaism is through new birth, not physical birth.
In Colossians 2:11, Paul says that spiritual circumcision was done by God without the hands of man. This circumcision, that was made without hands, proves that it was not done in the physical. Paul is referring to the spiritual circumcision of the heart. The sins of our heart were cut away and discarded through the sacrifice of Christ in a similar way that the foreskin is removed from a male. The physical act of circumcision is a picture of the spiritual circumcision that is now a reality in every born-again believer.
The condition of a person's flesh is not the important thing. It doesn't matter if the flesh is circumcised or holy. It is the condition of the spirit that matters with God. Those who put faith in their circumcision to save them are putting confidence in the flesh and not in God. Today, the act of circumcision is not the issue, but acts of holiness are still deemed by many as essential for receiving salvation. That is just as wrong as those in Paul's day who believed that being circumcised granted them salvation.