Martin Luther may be most remembered for rediscovering Paul's message of "justification by faith through grace" in the epistle to the Romans, but Luther himself held a different letter of Paul's closest to his heart. Luther called Galatians "my own epistle, to which I have plighted my troth. It is my Katie von Bora." Clearly, Luther discerned something more in this epistle than just another of Paul's lectures to a fractious, fragmented congregation of would-be Christians.

The whole of Galatians forms a fairly coherent, progressive argument by Paul against the teachings and influences of a rival faction. While theologically rich in their own right, the first four chapters of Galatians are really a series of examples and citations about the law and the gospel leading up to the climax of Paul…