Many old covenant rituals have a fulfilment in the new covenant. Circumcision was a very important ritual under the old covenant. Surely, such an important ritual must have a significant spiritual meaning in the new covenant - and it does.
Its meaning is described for us in Philippians 3:3, 4: "We are the true circumcision who worship in the Spirit of God, glory in Christ Jesus and put no confidence in the flesh" . These three expressions are all related to each other. To worship in the Spirit is to glory in Christ alone and is manifested by a life where we have no confidence in the flesh.
In physical circumcision people cut off a part of their physical flesh. In spiritual circumcision, we cut off our confidence in the flesh (our Self-life) and put it to death. In the Old Testament those who were not circumcised could not be a part of Israel ( Gen.17:14 ). In the New Testament, anyone who has confidence in himself cannot be a part of the true church of Jesus Christ. Only those whoglory in Christ alone and have no confidence in themselves are part of the true church. If we glory in the fact that we have built our church better than what others have built, God will have no place for us in His true church.
Acts 7:41 speaks of people who glory in the work of their own hands. If we boast in what we have accomplished, then we are spiritually uncircumcised. If you feel that you yourself have accomplished something, then your faith has failed. Then God in His love for you, will allow you to "fish all night and catch nothing" ( John 21:3 ), in order to teach you that true faith means a total dependence on Him alone.
One day Nebuchadnezzar stood on the roof of his palace and gloated over the great kingdom of Babylon that he had built ( Dan.4:29 , 30 ). As soon as he thought like that, God removed his kingdom from him and made him like an animal. It took him many years thereafter to be restored to sanity. Like him, many believers also gloat inwardly over what they have accomplished for God. But Nebuchadnezzar finally repented of his folly and glorified God ( Dan.4:34-36 ). He was finally circumcised in heart. The sad thing is that many Christian leaders have not experienced this spiritual circumcision.
God wants us to be circumcised in heart so that we can love Him with all our heart ( Deut.30:6 ). That is the mark of circumcision of the heart. We are not circumcised if we love ourselves and glory in ourselves.