Christians have always faced the problems of legalism and antinomianism. Legalism tries to thwart sin and promote holiness through imposing a law code that adds to Scripture. Of course, Paul addresses legalism in Galatians due to the false teachers who wanted to circumcise Gentile believers even though God never says Gentile disciples of Christ must become Jews (proselytes, Gal. 5:2–6).
Those who embrace antinomianism misinterpret Christian liberty, seeking to eliminate standards entirely. Antinomians indulge their flesh, which refers to human nature in rebellion against the Lord (Rom. 8:8). Legalism is a common response to antinomianism, and Paul defines the true way not to indulge the flesh in today’s passage, answering the Galatian Judaizers who bolstered their appeal to the Law by saying that keeping it is the only way to avoid sin.
Most legalists try to be faithful to God’s call to be holy (Lev. 11:44), but their good intentions do not produce right results. For as Paul tells us, the only way to keep from gratifying the desires of the flesh is to “walk by the Spirit” (Gal. 5:16). The basic idea here is that the Christian life is one defined by the fruit of the Spirit, which fulfills the Law (v. 22). We are to be constantly dependent on the Spirit for living in a manner pleasing to God. Again, a life under the Law is not a life without any directives. Paul talks about the Spirit-led life and fulfilling the Law through love in the same context (vv. 13–15), indicating that to walk by the Spirit produces a manner of life characterized by love for God and neighbor, the two great commandments (Matt. 22:34–40).
Living in the Spirit is incompatible with living in the flesh — with being dominated by sin — since the flesh and the Spirit are at odds with one another (Gal. 5:17). It is not a life free from all sin, for we will fall into transgression on occasion until death (1 John 1:8–9). But it is a life in which evil does not reign because the Holy Spirit Himself compels us to follow God’s will (Jer. 31:31–34). We who walk by the Spirit uphold the Law, not in our own power but in putting to death any idea that we can keep our Creator’s law in our own strength and drawing upon the Spirit’s might to make us please the Lord (Eph. 5:18).