"No distrust made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, fully convinced that God was able to do what he had promised" (Rom. 4:20-21, ESV).
"By faith Abraham obeyed when he was called to go out ..." (Heb. 11:8, ESV).
"... The only thing that counts is faith expressing itself through love" (Gal. 5:6, NIV, italics mine).
The theme of James is that "the faith you have is the faith you show!" You may indeed have faith to move mountains, but don't just brag about it! You can boast of great faith, but if it accomplishes zilch, what good is it? James would say to us that he wanted to show his faith by his good deeds or works; Paul, on the other hand, would show us his works by faith--these are two complementary assertions, depending on which side of the coin you see. James is appealing to do-nothing believers, who won't practice their faith and put it into action; while Paul sees believers who are trying to justify themselves by the works of the law--no one shall be justified by the works of the law, but by grace through faith in Christ alone--it's not how much faith, but the direction of it per Ephesians 2:8-9.
It has been wisely put by theologians that saving faith is only manifest in obedience: Dietrich Bonhoeffer said, "Only he who believes is obedient; only he who is obedient believes." Obey wholeheartedly! We must not legalistically obey out of obligation rather than love, like Amaziah, who did what was right in the eyes of the LORD, but not with a whole heart (cf. 2 Chron. 25:2). The two are correlated and what God has joined together, let not man put asunder (cf. Mark 10:9).
You can no more separate faith and works than your body and spirit--they are distinguished, but not separated--we are not a soul encased in a body, but a soul and body unified in one being, as distinguished; however, if you separate the soul and body, you're dead--likewise with faith and works. We must translate our creeds into deeds to be alive in the Spirit. Anyone can say he has faith, and faith is not being credulous, for we don't believe in spite of the evidence--we have sound reasons to believe--but in obey despite the consequences!
Some imagine that great faith necessitates great emotion, but this is not always the case, God may withdraw feelings to see what is on your heart and to test your obedience. Faith, then, is not walking around on some religious or spiritual "high," or around on cloud nine, but being in fellowship with God, being in touch with reality and the real world, and reacting according to God's will. We cannot have a religious ecstasy or euphoria and walk around in its glow the rest of our lives; we must learn to grow in our relationship with Christ and in our knowledge of Him and in grace itself, in order to become vessels of honor and to live our lives in glory to Him as our purpose (cf. Isaiah 43:7).
True faith is not accepting our "fate," but walking in obedience to whatever God wills and making no plans without consulting Him. Even David knew the pits of despair and what being downcast or having the doldrums meant, so much more must we to grow, but our victories will be all the more sweet after we know what defeat is and the price it cost Christ and the discipline it takes.
Martin Luther wondered if James was an epistle "of straw" because he thought it was teaching salvation by faith plus works. Actually, we are saved by faith alone (though these exact words are not in the Bible, it's taught), according to the teaching of the Reformers, but not by a faith that is alone. Dead faith doesn't save and isn't profitable (cf. James 2:17,20,26), and we need a living faith--a little is a lot with God in it, implying that it grows and thrives. James aptly said that the kind of faith that doesn't produce cannot save, period! Roman Catholics believe grace, faith, and Christ are necessary, but not sufficient--you must add merit to grace, works to faith, and the Church to Christ, not to mention adding tradition to the authority of the Word as equal validity.
We want to see faith in action in our family of believers, even as we are the ambassadors of Christ in the world, and people want to see the gospel in shoe leather, as it were, and this means the only gospel some will see is the one we live out--that's why it's paramount to practice what we preach and to keep our testimony from becoming jeopardized.
Some say that talk is cheap (we must beware of mere lip service, as in Isaiah 29:13, which Christ condemned, too), but we are called to preach the gospel not only by our lives as a witness, but in our words, and sometimes we are called to listen as the greater gift, but our testimony is fundamental: Actions can speak louder than words!
We must look for the open door to be lead by the Spirit in our witness and then it will be the Lord speaking through us as we are led by the Spirit. Actions open the door to preaching the Word and usher us into the presence of God and the open door. We are not to become mere do-gooders or be known as a goody-goody, but to live out the works that Christ has ordained for us that we should walk in them (cf. Eph. 2:10). Faith, then, is not something you have, but something you show--we say, "Show me your faith!" Remember, Romans 2:6 says we will be judged by our works, not our faith! If you have no good works, your faith is suspect, because if there's no fruit, there's no faith!
I'm not advocating a "works religion," but one proved by its works; in a works religion you never know how much is enough--we don't do works in order to get saved, but because we are saved out of gratitude. Our works must be consistent with our talk, as we don't just talk the talk: "They profess to know God, but they deny him by their works..." (Titus 1:16, ESV). The point is that faith expresses itself! In sum, Works are no substitute for faith, but the only evidence that it's there. We are not saved by works, but unto works, and, though we are not saved by works, we are not saved without them either! There are works without faith, but not faith without works! Soli Deo Gloria!