"and in Him you were also circumcised with a circumcision made without hands, in the removal of the body of the flesh by the circumcision of Christ; having been buried with Him in baptism, in which you were also raised up with Him through faith in the working of God, who raised Him from the dead." (Colossians 2:11-12)As part of the process of making us complete in Christ, we need to be recreated in Christ; we need to be changed from our former nature into a nature that is made after the image of Christ. Paul refers to this process as circumcision; not physical circumcision but spiritual circumcision.
The practice of circumcision is very ancient and served as a mark of the covenant made between God and Abraham and the children of Israel. "This is My covenant, which you shall keep, between Me and you and your descendants after you: every male among you shall be circumcised." (Genesis 17:10) Circumcision was a physical mark in the flesh in the removal of a piece of flesh often associated with our lusts and passions. However, while it stood as a sign of God's covenant with Israel, God always desired more. God desired a circumcision that was internal not external. Even before the children of Israel ever entered the Promise Land, God commanded them, "So circumcise your heart, and stiffen your neck no longer." (Deuteronomy 10:16) And God promised that if they would obey Him then He would "circumcise your heart and the heart of your descendants, to love the Lord your God with all your heart and with all your soul, so that you may live." (Deuteronomy 30:6)
God desires not the circumcision of our flesh but the circumcision of our heart; an inward circumcision that only He can perform within us. Paul writes clearly on this matter when he said, "For he is not a Jew who is one outwardly, nor is circumcision that which is outward in the flesh. But he is a Jew who is one inwardly; and circumcision is that which is of the heart, by the Spirit, not by the letter; and his praise is not from men, but from God." (Romans 2:28-29) This is a circumcision made without hands and in a place that no one can see. However, it's mark is evident to God and to all who truly examine our lives. It is an indelible mark that we are His and that our life has been changed by His hands.
This circumcision, this putting off of the flesh, happens when we are baptized. In baptism we are united with Christ in His death and resurrection; not figuratively but actually. Baptism is not an outward sign of an inward grace, it is an inward grace. In baptism our old man, our body of sin, is put to death and buried in a watery grave so that, as we rise from baptism, we also rise to newness of life. Paul teaches us concerning baptism, "Therefore we have been buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life. For if we have become united with Him in the likeness of His death, certainly we shall also be in the likeness of His resurrection, knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin; for he who has died is freed from sin." (Romans 6:4-7)
What makes baptism effective, what allows the performance of the circumcision of our heart, is not our obedience but our faith; faith in the working of God. Obedience appeals to the praise of men while faith appeals to the praise of God. Our faith rests not in ourselves but in the power of God that was sufficient to raise Jesus from the dead. If God can raise Jesus from the dead, surely He can also raise us to newness of life. Jesus came to make us complete and completion lays just ahead of us, but we must first pass through the waters of baptism, being circumcised in our heart, that we might receive and walk in newness of life.