There is an interesting structure to the book of Galatians. Paul is, of course, writing this letter because of the threat of the Judaizers who came in to spy out the liberty of the Christians. The Judaizers were saying that one needed Christ and law-keeping (as represented by circumcision) to be accepted by God. The apostle Paul, as you well know, would not tolerate this perversion of the Gospel for even one minute. Therefore, in his defense of the Gospel and it implications he draws several contrasts. They are as follows:
Chapter 2 : Faith not Works
Chapter 3 : Promise (Gospel) not Law
Chapter 4 : Sons not Slaves
Chapters 5 and 6 : Spirit not Flesh
The logical connection between these contrasting principles forms the basis for the argument of the epistle. If one is to be justified (accepted by God as righteous) it must be by faith, not by works. The reason for this is the difference between the promise and the law. Once someone has been justified by faith he has been adopted into God’s family–he is a son of God, not a slave. The freedom that we have by faith in Christ, that makes us sons, is not a freedom to live in the flesh (i.e. the sinful, natural, unconverted lifestyle). We are given the Spirit when we believe and we are called to walk in the Spirit. Chapter 5 is most properly a discourse on the agency and nature of sanctification. If we are in the Spirit our lives will reflect “faith working through love.” The context is not about how we are accepted by God, but how we live once we have been given the liberty of the sons of God. Understanding the contrasting principles of Galatians is the most important thing we can know.