In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
(
Colossians 2:11)
We are circumcised in Christ. It is only by being in Christ that we are circumcised with that spiritual new covenant circumcision.
Repentance and regeneration are necessary for being placed in Christ. Repentance, water baptism, and Spirit baptism are what puts us in Christ.
One cannot be in Christ apart from repentance, or water baptism, or Spirit baptism, it takes all three.
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)
Paul states that Gentile believers who keep the righteousness of the law are reckoned by God as being 'circumcised'. Who keeps the righteousness of the law?
For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh: That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit. For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit. For to be carnally minded is death; but to be spiritually minded is life and peace. Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be. So then they that are in the flesh cannot please God. But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
(
Romans 8:3-9)
The righteousness of the law can only be fulfilled by those who walk not after the flesh, but after the Spirit. This can only be truly done by those who HAVE the Spirit dwelling in them.
And thus is shown the connection between new covenant circumcision and the Holy Ghost, and between new covenant circumcision and obedience to God (implied in repentance from dead works and faith towards God).
For in Christ Jesus neither circumcision availeth any thing, nor uncircumcision, but a new creature.
(
Galatians 6:15)
Physical circumcision or uncircumcision accomplishes nothing, what it is important is
regeneration. And regeneration, becoming a new creature, requires repentance, water baptism, and Spirit baptism.
Circumcision represents the putting away of sin. How is that done?
First, it is something we do in repentance. We must put off the deeds of the flesh, the 'body of sin', we must turn from disobedience and unbelief and turn to God in faith and obedience.
It is also something that God does, He removes the stony heart from us, He delivers us from the power of sin by the power of the cross, He writes His laws into our hearts and minds.
It is something we do in baptism, whereby our sins are 'washed away' and the debt we owe (ie the guilt we have incurred) is remitted or forgiven or removed. We identify with Christ in his death, burial, and resurrection by being baptised in His name. The body of sins is 'removed' by the decree of God in remitting our sins.
It is something God does when He puts His Spirit in us - He gives us a 'new heart', He 'purifies our heart', He puts His Spirit in us and causes us to walk in His statutes and commandments. The Spirit of God is said to be that by which we are 'sealed'. Circumcision was the 'seal' of the old covenant, and the Holy Ghost is said to be the seal of the new covenant saints.
Obedience to God's commandments was also the 'seal' or 'sign' of the old covenant, and it is the seal or sign of the new covenant as well (as shown by Paul's teaching in Romans, as well as by the symbolism in Revelation showing the 'servants of God being sealed in their foreheads').
In short, being born again, being a Christian, being a member of the new covenant, having repented and having been baptised in the Lord's name and having been filled with the Holy Ghost are all part of being 'circumcised' under the new covenant.
Attempting to dissect salvation into separate component arts, like repentance, faith, baptism, Spirit filling, holiness, sanctification, justification, etc etc leads to weird and quirky theology. The apostles had no problem 'conflating' all these things, obviously because they viewed salvation holistically, as a whole rather than as a collection of separate parts.