Paul mentions three details that are always present when true discipleship is found: they are (a) service of God in the Spirit, (b) glory in Christ Jesus, and (c) no confidence in the flesh. Before we think about each of these details, we should note that Paul describes such worshippers as ‘the circumcision’. When he describes believers in this way, he means that they are in covenant with God.
Those who have such a commitment serve God in the Spirit. Paul is not limiting worship here to church services. Instead, what he means by worship is all of life. He is concerned with what we do on Mondays as well as on the Lord’s Days. The Christian life should be one ongoing life of worship and service. In Romans 12:1-2, Paul describes Christian worship: ‘I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship. Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect.’
The second feature of a true commitment is boasting in Jesus Christ. Such an attitude involves an understanding of who Jesus is and what he has done, is doing, and will do for his people. All that he does has been summarised for us in what we call the offices of Christ: a prophet to teach us; a priest to intercede for us and to exercise compassion on us; a king to rule over us and to defend us. There is much in these roles to cause us to boast in Jesus Christ.
The third feature of a true commitment is no confidence in the flesh. Paul proceeds to say why he could have had such confidence and he mentions aspects of his life from before his conversion (vv. 4-8) and after his conversion (vv. 11-13). Before conversion, he had status, racial privileges and earnest zeal; after conversion he had many spiritual attainments. But he did not build his hopes on them.