The entries for this chapter draft have been:
The Setting of Galatians
The Message of Galatians
Mid-stream the dam of my mind broke and I surrendered the North Galatian hypothesis, due mainly to the prodding of Richard Fellows this past year. So the first entry above will be edited appropriately. Still many questions, of course.
Normally, those applying the book of Galatians immediately talk about the freedom we have in Christ from the oppression of our sin and failure. We do not have to worry about being good enough or smart enough, because God likes us. Certainly there is a lot of truth to these applications. Certainly we should be immensely grateful for a God who is gracious and compassionate, slow to anger and abounding in love (Jonah 4:2). As Paul says in Romans 4:7-8, quoting Psalm 32, "Blessed are those whose iniquities are forgiven, and whose sins are covered; blessed is the one against whom the Lord will not reckon sin."
At the same time, this teaching has often been presented in incorrect and unhelpful ways. For example, Paul has often been pitted against a legalistic Judaism that believed you had to earn your right status with God. Against this idea of "works-righteousness," they say, Paul comes with the revelation that you cannot be saved by your good works but by faith alone. Similarly, Martin Luther is championed by Protestants as setting the Roman Catholic Church straight, where he like Paul recognized the truth of justification by faith alone while the Catholics believed good works were necessary for salvation.
Again, there is some truth to these scenarios, although they do skew history a little. For example, the Jewish literature we have from the ancient world generally shows that Jews also believed it was only the grace of God that made a good relationship with God possible for them. They of course put a high premium on living a righteous life in response to God's grace, but so does the New Testament, if we are willing to listen to it.  The main difference is the centrality of Christ in procuring God's favor and the way Paul emphasizes the Holy Spirit as how one is empowered to live that righteous life.
The Roman Catholic Church has also dialogued significantly with the Lutheran Church in recent years and has acknowledged that justification is first and foremost on the basis of faith.  But it also insists that good works must follow for final salvation. When we get to 2 Corinthians in chapter 10 and then later come to Romans in our second volume, however, we will find that Paul himself says some similar things. Paul never actually uses the expression "justification by faith alone." That phrase comes rather from Martin Luther. 
Galatians does carry a warning to the legalistic. Legalism is not a matter of being conservative or being strict in your lifestyle. Legalism is an attitude that enjoys rules for their own sake and puts rules above the people they are meant to benefit. If Paul seems a little inconsistent, it is because he knows what God wants but brings different arguments at different times to get his audiences there. So he knows the Gentiles can be in by faith. He knows that Jewish and Gentile Christian should eat together. He wrestles to show these truths in the different situational arguments of his letters. 
One way we might summarize Paul's argument here is that people trump the rules, even sometimes the rules of Scripture. The purity regulations that drove the argument between Paul and Peter at Antioch were surely over how to play out the purity regulations of Leviticus. But the rule of the unity of Christians required that exceptions be made to those rules. Indeed, Galatians 4:9 seems shockingly to equate keeping the Jewish Law with enslavement to evil spiritual forces that hold power over the basic elements of the world.
Certainly Paul was an apostle, and we are not, but he shows at times a shocking liberty in the way he reinterprets Scripture to counteract his opponents. One of the most striking is his allegorical interpretation of Sarah and Hagar, the wife and concubine of Abraham respectively. Perhaps his opponents have used them as a parable of Jew and Gentile. Paul counters by allegorically considering Sarah the heavenly Jerusalem with Hagar the earthly one. Those who put too much primacy on the earthly city are enslaved like Hagar, while those who are part of the heavenly Jerusalem are free like Sarah.
Galatians is thus more than a reminder that God does not strictly judge us on how good we are but on our willingness to trust in His mercy. It is a reminder that, in our attempt to serve God, we can subtly find ourselves using Scripture and our traditions to undermine God's more fundamental purposes. The "fundamentalist" interpreters of the early 1800s had great biblical arguments why slavery was a perfectly legitimate Christian institution. Do not the household codes of Colossians and 1 Peter assume slavery and tell slaves to obey their masters? It was those like Paul who were able to see the more fundamental spiritual principles--more central than random verses--who pushed back against slavery. And so we have moved closer to the kingdom.
A similar battle is currently in play between those who believe God might call women to play any role of any kind in the church or the home. Once again, they have their verses in the household codes or in 1 Timothy. But there is little doubt in my mind as to where the church as a whole will move soon enough, following the more fundamental principle that "in Christ there is not male and female" (Gal. 3:28, my translation).
Another important principle we will return to both in this volume and the next is the importance of not allowing one's freedom to become an opportunity for sin. Galatians 5:16 is quite stark, "Walk in the Spirit and you certainly will not fulfill the desires of the flesh" (my translation). Here we find no pessimism of regular moral failure, no sense of sinning every day in word, thought, and deed. What we find rather is an optimism of the Spirit's power, that if we will only open ourselves up to the empowerment of the Spirit, we will find the fruit of the Spirit permeating our lives.
 Thus E. P. Sanders' famous line, keeping the Law for Jews was "about staying in, not getting in." We add to our list of books to master Paul the follow up to his first book, Paul, the Law, and the Jewish People (**).
 "Joint Declaration" ***.
 Indeed, the only place we find this expression is in James, which says that a person is not justified by faith alone (Jas. 2:24).
 Sanders put it this way, Paul argues from solution to problem. He knows that Christ is the answer, but he struggles to express the precise nature of the problem Christ solves. See his Paul (**).