James is not saying, let's all go try harder! That would be the wrong thing to take away from this. He is not saying, let's try to do good works now to show we really have faith. That is not what James is saying. James is asking: are you really trusting in Christ? I like John Piper's definition:
Thomas Schreinerfaith is being satisfied with all that God is for us in Jesus.That is what faith is; it embraces Christ. That is what James is calling us to do: to be satisfied in Christ, to feed on him. Our works will show whether we are satisfied.1
18 But someone will say, “You have faith and I have works.” Show me your faith apart from your works, and I will show you my faith by my works.