While we have seen that the law is ineffectual against sin, and (as Paul argues) that the law promotes sin in sinful flesh, and while we have just seen that it is love that fulfills the two tables of the law, we then must ask, “What, according to Paul, produces growth in holiness?” And that brings us to the great antithesis between the Spirit and the flesh that Paul expounds in Galatians 5. Let’s emphasize once again that Paul is writing to the church. He is not writing a treatise solely on justification by faith. He reminds the Galatians, as we noted above, “You were running well!” These are believers that Paul is cautioning against turning from the Spirit.
 But I say, walk by the Spirit, and you will not gratify the desires of the flesh.  For the desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh, for these are opposed to each other, to keep you from doing the things you want to do. (Gal 5:16–17)
While the struggling man of Romans 7 may or may not be a representative of the unregenerate man facing despair in trying to obey the law, the man addressed by Paul is one who fights the Christian fight, the war between the flesh and the Spirit.
 But if you are led by the Spirit, you are not under the law.  Now the works of the flesh are evident: sexual immorality, impurity, sensuality,  idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions,  envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God. (Gal 5:18–21)
There is a connection between living under the influence of the law and living in the flesh. Paul has already explained to us that the law promotes sin in man’s flesh, and Schreiner explains Paul’s argument:
Those who “are led by the Spirit … are not under the law.” (Gal 5:18). Those who yield to the Spirit are free from the law. For Paul, being under law is the equivalent to being under the power of sin (cf. Rom. 6:14–15). His point is not that those who live in the Spirit are free from all moral norms or moral constraints, as if those who live in the Spirit enjoy unbridled freedom. Instead, those who yield to the Spirit conquer sin and live in love. Those who are still subject to the law end up producing the works of the flesh (Gal 5:19–21). Those who are led by and walk by the Spirit produce the fruit of the Spirit (Gal. 5:22–23). And what is the fruit of the Spirit? The fruit of the Spirit is not created by inspecting fruit. The perpetually penitent believer (see Completed by the Spirit Part 4) who “repeatedly condemns himself, deplores his wretchedness and despairs over his lack of sanctification” is working against the Spirit and trying to fix himself in the flesh. It is the one who relies on the Spirit who obtains the joy that Paul describes; not the one in bondage to self-condemnation:
 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness,  gentleness, self-control; against such things there is no law.  And those who belong to Christ Jesus have crucified the flesh with its passions and desires.
 If we live by the Spirit, let us also walk by the Spirit. (Gal 5:22–25)
That walk by the Spirit finds its prototype in Jesus Himself declares Sinclair Ferguson, who writes:
The fact that Jesus was the Man of the Spirit is, therefore, not merely a theological categorization; it was flesh-and-blood reality. What was produced in him was fully realized human holiness. He was the incarnation of the blessed life of the covenant and of the kingdom-beatitudes which are its fruit. Meyer makes a connection between the call in Romans 7 to “serve in the new way of the Spirit and not in the old way of the written code,” and the fruit of the Spirit:
Bearing fruit for God means serving in the newness of the Spirit. That is, the Spirit gives birth to newness and fuels “new life” further. … The comparison between “fruit” and “newness” is enlightening for the whole discussion. Fruit grows on a tree because of the root system that causes its growth. The root system accounts for the origin of the fruit (i.e., gives birth to the fruit) and acts as the catalyst that causes further growth (i.e., providing the water and nutrients that are necessary for growth). In the same way, the Spirit accounts for the origin of new life (Spirit creates new life) and acts as the catalyst for future life (Spirit produces new life). … “In newness of the Spirit and not in oldness of the letter” of Rom 7:6 is comparable to the phrase “ministers of a new covenant, not of the letter but of the Spirit” in 2 Cor 3:6. The Holy Spirit working in the God-Man Jesus Christ produced the prototype for our glorified selves. That which we will one day be in glory has been given to us now in the Spirit within us.
We strive to be that which we already are by walking in the Spirit until the time when Christ “will transform our lowly body to be like his glorious body” (Phil 3:21).
We do not do it by becoming slaves to sin, we do not do it by becoming adulterers now that the King has come for His betrothed, and we do not do it through anguished, externally-driven, dismal self-righteousness produced by the dangerous doctrine of the third use of the law.
Next: Completed by the Spirit Part 16: Exhorted in our Union With Christ
 Thomas R. Schreiner, New Testament Theology: Magnifying God in Christ (Grand Rapids: Baker Academic, 2008), 484.
 Sinclair B. Ferguson, The Holy Spirit (Downers Grove, IL: 1996), 52.
 Jason C. Meyer, The End of the Law: Mosaic Covenant in Pauline Theology(Nashville: B&H Publishing Group, 2009), 47–8.