Colossians 2:9-11, "For in him dwelleth all the fulness of the Godhead bodily. And ye are complete in him, which is the head of all principality and power: 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:" In the Old Testament, circumcision was the sign that the individual Israelite stood in a covenant relationship with God. It symbolized a cutting away or separation from sin and all that was unholy in the world. The believer under the New Testament covenant has undergone a spiritual circumcision, namely, the removal of "the body of the sins of the flesh." Such circumcision is a spiritual act whereby Christ cuts away our old unregenerate nature of rebellion against God and imparts to us the spiritual or resurrection life of Christ. It is a circumcision of the heart.
This correlates with what Paul also wrote in Romans 2:28-29. "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." This refers to God's work of grace in the hearts of believers whereby they partake of the divine nature and become capable of living a pure life separated from sin for the glory of God! 2 Peter 1:4, "Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust." As believers, we partake of the very nature of God. Our sharing in His nature is another description of the new birth by which we receive the life of God. We share God's nature in order to conform to God and to His holiness. Thus, holy living becomes the outward sign that we are under the new covenant. (Commentary from the Life in the Spirit Study Bible)
This correlates with what Paul also wrote in Romans 2:28-29. "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." This refers to God's work of grace in the hearts of believers whereby they partake of the divine nature and become capable of living a pure life separated from sin for the glory of God! 2 Peter 1:4, "Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust." As believers, we partake of the very nature of God. Our sharing in His nature is another description of the new birth by which we receive the life of God. We share God's nature in order to conform to God and to His holiness. Thus, holy living becomes the outward sign that we are under the new covenant. (Commentary from the Life in the Spirit Study Bible)