The possession of the Spirit shows that we have a right to the inheritance, because the Spirit brings righteousness, and the inheritance is one of righteousness. Righteousness, and that only, will dwell in the new earth. Rom 8:9-11,16-17, Eph 2:22, Rev 21:7, Rev 22:4,17
In harmony with the above text, we have also the following: “And ye are complete in Him (Christ), 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.” Col 2:10,11
Now the reason why this sign was given, which was only a sign, and which brought nothing to its possessor, and which was a false sign unless the righteousness of faith was in the heart, will be seen when we consider what had taken place after the covenant was made with Abraham. He had entered into an arrangement, the object of which was an inheritance a promise of the Lord. Abraham and Sarah believed that the promise was to be theirs, but they thought that they could work it out themselves. But since the promise was of an inheritance of righteousness, the thought that they could work it out was in reality the very common idea that men can work out the righteousness of God.
So when God repeated the covenant, He gave to Abraham a sign, which should always be a reminder of his attempt to work out the promise of God, and his failure. It did not give him anything, but was on the contrary a reminder that he could do nothing of himself, and that everything was to be done in him, and for him by the Lord. The cutting off of a portion of flesh showed that the promise was not to be gained by the flesh, but by the Spirit. Ishmael was born after the flesh, but Isaac after the Spirit. Gal 4:21, Eph 2:11-13. Col 1:27.
The same purpose was also served by it for his descendants. It was to keep continually before them the mistake of their father Abraham, and to warn them against making the like error. It was to show them that “the flesh profited nothing.” John 6:63 In after times they perverted this sign, and assumed that the possession of it was an assurance of their righteousness, whether they kept the law or not. They trusted that it brought them righteousness, and make them the peculiar favorites of the Lord. But the Apostle Paul showed the truth in regard to the matter by saying. “We are the circumcision, which worship God in the Spirit, and rejoice in Christ Jesus, and have no confidence in the flesh. Phil. 3:3. The Jews came to look upon it as bringing to them everything, because they trusted in their own righteousness, whereas its only object was to teach them not to put confidence in themselves. Gal 3:14, 26-29. E.J. Waggoner