Galatians 5:18

If we are led by the Spirit, we are not under the Law. This statement is a first class condition in the Greek text indicating that the writer assumed the statement was true for the sake of his argument. Other information about what he said determines whether it is really true. In this case Paul seems to have believed that the Holy Spirit does indeed lead every Christian (cf. Galatians 5:24-26; Romans 8:14). The question is, will we follow His leading and walk after the Spirit (Galatians 5:16) or will we walk after the flesh? The "if" in this sentence has the force of "since." However, we should not conclude that the Spirit forces us to do God’s will. He does not lead us that strongly.

The Holy Spirit leads us to do the moral will of God. He does this primarily through Scripture by helping us understand the will of God as He has revealed it there. Furthermore He motivates us to do what we know to be right, and He provides the power for us to obey God (Philippians 2:13). We can overcome the flesh by siding with the Spirit.

"Walking by the Spirit, the antidote to nomism [living by the law] of every kind, calls for resolution and staying power, as is made plain by Paul’s frequent use of athletic metaphor for the Christian life." [Note: Bruce, p. 246.]

"Being led by the Spirit does not imply passivity but rather the need to allow oneself to be led. Responding to the Spirit is described by three mutually interpreting words in Galatians 5:16; Galatians 5:18; Galatians 5:25 -’walk’ (RSV), ’led,’ and ’live.’" [Note: Boice, p. 495.]

We might have expected Paul to write that since we are led by the Spirit we are not "under the flesh," but instead we read "under the law." His point was that the Christian cannot overcome the desires of the flesh by remaining under the law. The Judaizers were advocating submission to the law as the way to overcome the flesh, but Paul advocated submission to the Spirit.