James, a servant of God and of the Lord Jesus Christ, to the twelve tribes in the Dispersion: Greetings. (James 1:1 ESV)
Right off the bat, we see a difference between James and Romans: conciseness. While Romans is written in the style of an elaborate theological treatise, James is short and to the point. James was also written something like 15 years or so before Romans. Which brings some interesting perspective to the evolution of the Christian faith, which we will look at later.
James is also, unlike Romans, written to a Jewish audience. This plays a big role in how we interpret James because, unlike the Roman Christians, who were mostly Gentiles and not accustomed to talk of law, the Jewish Christians to whom James is writing were. Obedience was a very important idea to them. While these Christians believed in Christ, their Jewish upbringing formed their version of Christianity much as our culture today forms ours.
In other words, these Jewish Christians are a lot like us in many ways.
Just as we have a hard time imagining Christianity without preachers and pulpits, the Jewish Christians James is writing to would have had a hard time seeing faith in Christ as something separate from works. They may have embraced faith in Christ alone as a theological and philosophical idea or at an intellectual level, but practically speaking, there was some cognitive dissonance between that idea and the Jewish emphasis on law and obedience they had grown up with. Similarly, we tend to squirm when someone “preaches” in an unconventional manner without a leather-bound Bible in their hands from behind a podium. We know they are not wrong for that, but we just have a hard time accepting it and may never fully embrace it as maybe we ought.
As a result, the theme through the entire letter is to encourage the readers to live as Jesus would call them to live. Jesus was impartial, he didn’t show favoritism, and He was obedient to the law. In fact, He fulfilled the Law. And, James would probably say, these are things which all should seek to do as well.