Please read the passage carefully.
Having identified freedom as Christ's gift to his followers, Paul now carefully defines just what kind of "freedom" this is and what it requires. Even though Paul calls on the Galatians to firmly resist once more being brought to submission beneath a “yoke of slavery” (v. 1), Paul insists that being “called to freedom” in Christ means that we are “through love [to] become slaves to one another” (v. 13). For Paul, freedom is not the opposite of slavery, but rather a matter of what one serves.
“Flesh” is that self-regarding human nature corrupted at its source, with its unchecked appetites and propensities, which result in the works of the flesh he will soon list.
Many commentators have noted how Paul's complex relationship to the law is demonstrated in the message he presents in verses 13 and 14. First, Paul emphasizes the power and priority of Christ's freedom and love over the letter of the law. Yet, in verse 14, he uses a popular encapsulation of the law itself to demonstrate correct behavior in those living within Christ's freedom. Some commentators have suggested that this reference to "the law" allows one to understand it as Paul's continued commitment to the "second table" of the Mosaic covenant - and the ethical/relational precepts spelled out there. Others claim Paul is stressing the difference between the concern of the opponents with doing the Law and his own urgings that Christians fulfill the law through love.
However, why should others be any more beneficial a master than one’s own self? Does not experience teach us that those who submit their own desires to the desires of others are often, if not perhaps universally, taken advantage of by them? The very real potential for such abuse may be exactly why Paul immediately asserts that the “whole law” can be reduced to the command, “You shall love your neighbor as yourself” (v. 14).
Paul and Jesus unite at the supremacy of love. In b.Sabb. 31a, we read of a Gentile coming to Shammai asking the rabbi to teach him the entire Torah while he stood on one foot. Shammai hit him with a rod that he had. When he went to Hillel, he responded, “What is hateful to you do not to your neighbor; that is the whole Torah, while the rest is commentary. Go and learn it. Judaism had other attempts to summarize or organize the Torah into shorter topics or sayings. Yet, that command applied individually (“I must love others as I love myself”) of course cannot stave off abuse.
Clearly, in verse 14 Paul uses the “law” in a positive sense. Most likely, he uses it in a way that corresponds to the use of the Hebrew word Torah within Judaism to refer to the “instruction” God provides through the Scriptures regarding how to live in relationship with the Divine, other people and all of creation.
In all of this, we can see the problem that Luther unnecessarily created for himself. He made such a sharp distinction between faith and love that there is legitimate concern that “faith” becomes only a matter of inner conscience, with little effect upon how one lives. In this, I think John Wesley had a better way of thinking, using these verses to say that Christianity is always faith working through love.
Verses 16-21 and 22-26 divide human behavior into that of the "flesh" and that of the "spirit.” Traditional interpretations of these two ways have tended to take Paul literally. One understands flesh as the base, fallen nature of human flesh. Likewise, one understands the spirit as a literal reference to living within the power and the influence of the Spirit of Christ, the Holy Spirit. Some scholars suggest that such a reading is too simplistic. This interpretation reads flesh and spirit as redemptive historical terms. For Paul, fleshly existence was something that trapped all people until the events of Christ's death and resurrection. Those who hear and believe the news of Christ's resurrection, however, now enter into a new plane of existence - living in the Spirit. In this model, the Mosaic Law was part of the old fleshly system that existed before Christ's redemptive death. Thus, when Paul argues against being in the flesh he is not simply citing flesh as an inferior human condition, but as a past standard that has been overwhelmed by the event of Christ's death and resurrection. Those still in the flesh are the opponents whose teachings are causing confusion and dissension in the Galatian church. Those in the spirit are all those who live the light of Christ's redemptive acts. To live in "the Spirit" is to experience the crucifixion of one's own flesh (v. 24) and thus to enjoy the new freedom Christ offers.
As Paul refers to the reign of God here, he refers to a future reality, the heritage of the people of God in the age to come. The gift of the Spirit is the guarantee or first installment of that heritage.
Verses 22-26 focus on the Spirit. Here are the graces that exhibit the lifestyle of those who live by the energy and indwelling of the Spirit. Even if we continue to read verses 16-25 as literal references to flesh and Spirit, there remains an undercurrent in Paul's words of the continuing battle between law and freedom.
If we examine the works of the flesh and the fruit of the Spirit, we can see that while the former disrupt fellowship and friendship, the latter build it up.