It is not certain, but it is most probable, that this verse should read, "Who worship by the Spirit of God." Not that this makes any great difference, for, as it stands, it means that worship must be inward and spiritual, springing from the heart, instead of being external and ritual, a matter of rites and ceremonies; and this could only be in the power of the Holy Ghost. Accepting, however, the emendation, the contrast with what precedes is all the more striking and complete. The apostle warns the saints at Philippi to be on their guard against the Jewish teachers who were seeking to subvert their faith: "Beware of dogs, beware of evil workers, beware of the concision." He will not say circumcision, although these Judaisers attached every importance to it, because, since the death and resurrection of Christ, it is in Him alone that the truth shadowed forth in the external rite of circumcision is realised. (Col. 2:11.) He therefore uses a term of contempt, and he then proceeds to say that we (we Christians) are the circumcision, who worship by the Spirit of God (not by rites and ceremonial forms), and rejoice (boast) in Christ Jesus (not in Moses, however honoured as a servant in God's house - Heb. 3), and have no confidence in the flesh (as those who prided themselves upon their circumcision had). We need not go further except to call attention to the abiding value of this teaching; for, whether it be ritualism or rationalism, both have their roots in confidence in the flesh. The latter may join in the agitation and outcry against the former, but both alike refuse to accept the end of man in the cross of Christ. They both 'alike, therefore, are antagonistic to Christianity. (See Col. 2.)
The inquiry as to whether this is a quotation or not raises a very interesting question, which can best be answered by a reference to a passage or two of a similar kind. In John 7:38, for example, the Lord distinctly connects the promise of the rivers of living water flowing out of the one believing on Him with what the Scripture hath said. But, search as you may, these exact words cannot be found, though doubtless the allusion is to Isaiah 58:11. Again, in Acts 13:47 we find the apostle justifying, on the Jews rejecting his message, his turning to the Gentiles by saying, "For so hath the Lord commanded us, saying, I have set Thee to be a light of the Gentiles, that Thou shouldest be for salvation unto the ends of the earth." This is an exact citation from Isaiah 49:6; but, as may be readily seen, the words are addressed by Jehovah to the Messiah, His Servant, when in the sense of His rejection by Israel. In both of these scriptures it is the spirit, not the letter, which is before the mind in its application to the subject in hand, and which, as thus used, carried with it divine authority. So in the passage from Ephesians there can be little doubt that Isaiah 60:1 was in the mind of Paul. There we read, "Arise, shine; for thy light is come, and the glory of the Lord is risen upon thee." The Redeemer is come to Zion (59:20); His glory has risen upon her, and the prophet calls upon her to arise and shine with the light that has thus come; he says in verse 19, "The Lord shall be thine everlasting light," etc. In like manner the apostle, after exhorting the Ephesian believers to have no fellowship with the unfruitful works of darkness, and pointing out the effect of light in manifesting the character of everything, calls urgently upon them to bestir themselves: "Awake" (up!), "thou that sleepest, and arise from the dead, and Christ shall shine upon thee." If any among them were having fellowship with the unfruitful works of darkness, they were morally sleeping (compare 1 Thess. 5:6), and outwardly with those who were in spiritual death. Hence the rousing exhortation to awake and to arise from the dead, that the light of the glory of Christ might shine unhinderedly upon their souls with all its transforming power through the Spirit. (See 2 Cor. 3:18.) Understood in this way, there will be no difficulty in perceiving its correspondence with the scripture to which the apostle was guided by the Holy Ghost. The lesson is so important that it may be repeated - that the essential thing in dealing with the Scriptures is to apprehend their spirit; for, as the apostle elsewhere says, "the letter killeth, but the spirit giveth life. . . . Now the Lord is that Spirit: and where the Spirit of the Lord is, there is liberty." Perfect therefore as the letter is, and tenaciously as it is to be held fast, the essential thing for our souls is what underlies the letter.