“What use is it, my brethren, if a man says he has faith, but he has no works? Can that faith save him? If a brother or sister is without clothing and in need of daily food, and one of you says to them, ‘Go in peace, be warmed and be filled,’ and yet you do not give them what is necessary for their body, what use is that? Even so faith, if it has no works, is dead, being by itself.” (James 2:14-17)
Dead faith is hypocritical, shallow, and useless.
Jesus said, “Let your light shine before men in such a way that they may see your good works, and glorify your Father who is in heaven” (Matt. 5:16). Your righteous deeds illuminate the path to God by reflecting His power and grace to others. That brings Him glory and proves your faith is genuine.
Your deeds also serve as the basis of divine judgment. If you practice righteousness, you will receive eternal life; if you practice unrighteousness, you will receive “wrath and indignation” (Rom. 2:6-8). God will judge you on the basis of your deeds because what you do reveals who you really are and what you really believe. That’s why any so-called faith that doesn’t produce good works is dead and utterly useless!
James illustrates that point in a practical way. If someone lacks the basic necessities of life and comes to you for help, what good does it do if you simply wish him well and send him away without meeting any of his needs? It does no good at all! Your pious words are hypocritical and without substance. If you really wished him well, you would do what you can to give him what he needs! Your unwillingness to do so betrays your true feelings. Similarly, dead faith is hypocritical, shallow, and useless because it doesn’t put its claims into action—indeed, it has no divine capacity to do so.
From Drawing Near by John MacArthur