One preliminary note: If you’re making a list of Christian behavior do’s and don’ts, chapter 5 is a good place to start.
Chapter 1: Paul reprimands the Galatians for deserting Christ for a false gospel, and then gives a brief summary of how he (Paul) came to be apostle to the Gentiles (interesting, and includes his time in Arabia, etc.).
Chapter 2: Paul continues with more autobiography, in a way that sets the stage for his Jew/Greek, slave/free, male/female lesson in chapter 3. There’s a also a discussion here of justification through faith not law (2:16-21).
Chapter 3: Paul continues his discussion of how faith has superseded the law. But I wonder whether 3:24-25 is neglected: “Therefore the Law has become our tutor to lead us to Christ, that we may be justified by faith. But now that faith has come, we are no longer under a tutor.” The chapter concludes with this famous verse (3:28): “There is neither Jew nor Greek, there is neither slave nor free man, there is neither male nor female; for you are all one in Christ Jesus.”
Chapter 4: Paul returns to reprimanding the Galatians. It’s hard to tell just from the text precisely what prompted the reprimand, but there is much discussion of law-versus-faith, climaxing with verse 5:14, “For the whole law is fulfilled in one word, in the statement, ‘You shall love your neighbor as yourself.'” (By the way, 4:13 contains a reference to some ailment of Paul’s.)
Chapter 5: After finishing the reprimand as just discussed, Paul urges that we ‘live by the Spirit” (5:16) rather than the “deeds of the flesh,” and that those who embrace the latter “will not inherit the kingdom of God” (5:21). The “deeds of the flesh” are “sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like” (5:19-21). On the other hand, the “fruit of the Spirit” is “love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control” (5:22-23). And “[l]et us not become conceited, provoking and envying each other” (5:26).
Chapter 6: Some pithy verses here: “For each one shall bear his own load” (6:5). “Do not be deceived, God is not mocked; for whatever a man sows, this will he also reap” (6:7) — that is, there will be “corruption” [meaning in this context, I think, bodily decay] to those who sow to the flesh, but “eternal life” to those who sow to the Spirit (6:8). And “let us do good to all men and especially to those who are of the household of the faith” (6:10, emphasis added).