I think James is writing before Paul. I agree with those who say that James is writing around 46 AD. Thus, he is not responding to Paul here. Paul has not even written his letters yet. This is not a response to Paul and a reaction to him. James is only trying to show what Christians always need to hear: genuine faith makes a difference in people's lives. That is what he is trying to show. We need to remember that Paul writes against legalism; against those who are trying to merit right standing before God on the basis of their works. Paul emphasizes that we can only be right with God by faith, by receiving the righteousness that comes from Christ. At the Lord's Supper we celebrate that none of us is righteous in and of ourselves, and that our righteousness comes from Another. Since we are all sinners, none of us can enter into God's presence on the fundamental basis of what we do.
James does not disagree with that. James is just writing not against legalists, but against Antinomians. Antinomians are the people who are against God's law. Those who say it does not matter how we live after we are Christians. Those who say that once you believe, you are saved—no matter what you do. I have even read about and heard people who have said, you can even become an atheist after you have become a believer, and you will still ultimately be saved. That is nonsense, isn't it? No, we cannot sin to our heart's content and still enjoy eternal life on the final day. James is not denying that we are saved by faith; he is simply saying, true faith can never exist without works.1
Thomas Schreiner
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.