At the time of the Protestant Reformation, Roman Catholic theologians leaned heavily on the second chapter of James to maintain that justification is not by faith alone but by faith and works. The Reformers were taking every opportunity to say that justification is a free gift, that we receive it by faith alone, and that Paul's letters to the Romans and to the Galatians back them up. But James seems at first glance to teach that works are necessary.
There is no conflict between Paul and James. Paul taught us that salvation is by faith alone, and James tells us that there is a true and a false faith. A man who "claims to have faith but has no deeds" is a man who has false faith. True faith shows itself in good deeds.
Thus, said the Reformers, we are justified by faith alone, but justifying faith is never found alone; it always brings forth good fruit. Men such as Luther and Calvin said that we are not justified by making a profession of faith but by possessing faith. A person who professes faith and then lives a life characterized by unrighteousness is surely deluding himself with counterfeit faith.
Faith is not "mere assent." Even the demons believe that God exists, said James, but rather than delighting in this knowledge, they respond with shuddering (James 2:19). The Reformers said that faith involves knowledge, assent, and trust or commitment. We must know something about God's truth, and we must assent to the truth of it, but if that is all we do, we are no better than the fallen angels. True faith goes beyond mere assent and involves a personal relationship of trust and commitment to God, and such true faith will always show itself in deeds of love and obedience.
James used the verb justify when he wrote, "Was not our ancestor Abraham justified for what he did when he offered his son Isaac on the altar?" (James 2:21). The Greek word justify can mean "legal justification," which Paul taught is received by faith alone, or it can mean "demonstrative justification," which was James' meaning here. Abraham's good work demonstrated his justification and filled up the legal justification that James, as well as Paul, said he received by faith (James 2:23).
One theologian has said that we must employ the theology of the second glance. Admittedly, there are passages which at first seem to imply the opposite of what one knows is orthodox. A more careful approach resolves apparent contradictions. Thank God for teachers who clearly explain the one way of salvation.