The covenant sign was cut into the flesh, and Moses promised a day God would circumcise hearts instead. Paul says that day came — the circumcision of Christ, made without hands.
The Shadow
God gave Abraham a covenant sign that could not be more personal: a cut in the flesh, carried for life, marking a man as belonging to the promise. But the sign always outran the reality. A man could carry the mark and not the faith — Israel's whole history proved it. So the law itself began pointing past the sign. Moses told Israel that the Lord your God will circumcise your heart, to love the Lord with all your heart and soul. The prophets picked up the theme: the cutting that mattered was inward, and no knife in human hands could reach it. The sign said belonging. The people needed becoming.
The Fulfillment
Paul announces that the promised surgery has happened. In Him you were also circumcised with the circumcision made without hands, by putting off the body of the sins of the flesh, by the circumcision of Christ. Notice everything about the grammar. It is past tense: were circumcised. It is passive: done to you, not by you. And it is His: the circumcision of Christ. At the cross, the old self you could never cut away was cut away — buried with Him in baptism, raised with Him through faith in the working of God.
This is why Paul fought so fiercely against requiring the old sign of Gentile believers. It was not a small ritual question. To reach for the knife again was to say the cross's surgery had not been enough.
Him All Along
Your standing in the covenant is not marked by anything you did, maintained, or endured. The mark is in Christ, made without hands, and it does not fade with a bad month. God performed on you what He asked of you — that is the shape of the whole New Covenant, and it is why the heart He circumcised is finally free to love Him back.