Notice that James begins this section by using the example of someone who says he has faith, verses 14. He then immediately gives an example of what true and false faiths are. He begins with the negative and demonstrates what an empty faith is (verses 15-17). Then he gives an example of the type of faith that isn't much different from the faith of demons (verse 19). Finally, he gives examples of living faith by showing Abraham and Rahab as the type of people who demonstrated their faith by their deeds.
James is examining two kinds of faith: one that leads to godly works and one that does not. One is true, and the other is false. One is dead, the other alive; hence, "Faith without works is dead," (James 2:20).
This is why in the middle of his section on faith and works, he says in verse 19, "You believe that God is one. You do well; the demons also believe, and shudder." James says this because the demons believe in God, that is, they have faith, but the faith they have is useless. It does not result in appropriate works. Their faith is only a mental acknowledgment of God's existence.
Ascentia and Fiducia
Two words are worth introducing here: ascentia and fiducia. Ascentia is the mental assent, the mental acknowledgment of something's existence. The demons acknowledge and believe that God exists. Fiducia is more than mental acknowledgment. It involves a trust in something, a giving over to it, a complete believing and acceptance of something. This is the kind of faith that a Christian has in Christ. A Christian, therefore, has fiducia; that is, he has real faith and trust in Christ, not simply an acknowledgment that He lived on earth at one time. Another way to put this is that there are many people in the world who believed that Jesus lived: ascentia. But they do not believe that He is their savior, the one to whom they should look and trust for the forgiveness of their sins.
Ascentia does not lead to works. Fiducia does. Ascentia is not of the heart. Fiducia is.
What is James Saying?
James is simply saying that if you ‘say' you are a Christian, then there had better be some appropriate works manifested or your faith is false. This sentiment is echoed in 1 John 2:4 which says, "If you say you have come to know Him, yet you do not keep His commandments, then the truth is not in you and you are a liar."
Apparently, there were people who were saying they were Christians, but were not manifesting any of the fruit of Christianity. Can this faith justify? Can the dead ‘faith' that someone has which produces no change in a person and no good works before men and God be a faith that justifies? Absolutely not. It is not merely enough to say you believe in Jesus. You must actually believe and trust in Him. If you actually do, then you will demonstrate that faith by a changed and godly life. If not, then your profession is of no more value than the same profession of demons: "We believe Jesus lived."
Notice that James actually quotes the same verse that Paul uses to support the teaching of justification by faith in Rom. 4:3. James 2:23 says, "and the Scripture was fulfilled which says, ‘and Abraham believed God, and it was reckoned to him as righteousness.'" If James was trying to teach a contradictory doctrine of faith and works than the other New Testament writers, then he would not have used Abraham as an example.
Therefore, we are justified by faith. That is, we are made righteous in the eyes of God by faith as is amply demonstrated by Romans. However, that faith, if it is true, will result in deeds appropriate to salvation. After all, didn't God say in Eph. 2:8-10, "For by grace you have been saved through faith; and that not of yourselves, it is the gift of God; not as a result of works, that no one should boast. For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them."