James, writing this letter to believers, is making the point that faith without works is dead and he shows it by using the demons as an example. The demons believe that there is a God but that belief in God does not help because it’s not a real faith and it is shown by their lack of works that go along with it. You can’t see one’s faith, so it is best demonstrated by their works.
I had a friend that would always tell me “I have faith, I have faith. I believe there is a God and I believe in Jesus Christ.” That’s all well and all, but it was hard to believe they had a real faith because I was not able to see their works. It’s important that our faith lines up with our works. That’s what James is trying to drive home to us today. Without our works, it’s hard for our faith to shine through. Demonstrate your faith by your works.
I’ll show you my faith by my works.