Romans 8:9, “You, however, are not in the flesh but in the Spirit, if in fact the Spirit of God dwells in you. Anyone who does not have the Spirit of Christ does not belong to him.”
Paul is a complex thinker, and his arguments often hold together several complementary truths without necessarily mentioning each of them specifically. One example of this is the Apostle’s discussion of life in the flesh and life in the Spirit.
Due to Paul’s teaching on our need to walk in the Spirit so as not to gratify the desires of the flesh (Gal. 5:16), we often think of living in the Spirit in purely subjective terms. We conceive of such life as pertaining only to what the Holy Spirit does in us as we follow Him in our sanctification. Yet the subjective experience of living according to the Spirit—while true and important—is not all that Paul has in mind when he talks about living in the Spirit.
In other words, there is an objective reality to life in the Spirit. Often, Paul’s contrast of flesh and spirit refers to a contrast between two ages—the era of sin and death associated with the administration of the old covenant and the Mosaic law’s inability to produce obedience versus the era of fulfillment that commenced with the coming of Christ. The age of the Spirit is characterized by freedom from sin’s power, peace with God via the imputation of Christ’s righteousness, and so forth. It is not that the believers who lived before Christ did not have access to these things. They did, though not with the same knowledge and fullness that we do. As such, the old covenant saints were really citizens of the new age of the Spirit who lived, as it were, outside of the actual time that they walked the earth. They walked the earth before the ministry of Christ, but they really belonged to the era of the Spirit in which we live. In any case, there has been a decisive change with the coming of Christ. The kingdom of God has been inaugurated, and the old era of sin and death is passing away as the new era of the Spirit becomes ever more present through the growth of the kingdom (2 Cor. 3; Gal. 4:1-7; see also Heb. 8). When Paul says we are in the Spirit, He often means that we have been brought into the new era of life and peace, that we enjoy the objective reality of justification and a righteous status before the Lord.
As noted above, life in the Spirit also has a subjective dimension. Once we lived in the flesh, being controlled by all that is against God, and could not please Him. However, because we have been transferred into the new era of the Spirit, we have received the indwelling presence of the Holy Spirit. The Apostle assures us that if we have trusted in Christ, we have the Spirit, and our possession of the Spirit proves that we belong to Jesus (Rom. 8:9).
Today’s passage helps us to understand that there is no such thing as a Christian who does not possess the Holy Spirit. To belong to Christ Jesus is to possess His Spirit, so if you have rested in Christ alone for salvation, the Holy Spirit does indwell you, and He is at work in your life. Let us remember this always, that we may be confident that the Spirit is working in and through us even when it is hard for us to see or feel it.