James, a disciple of Jesus, wrote “faith without deeds is useless” (James 2:20). He explains that people brag about their faith, but if that faith does not lead them to action, it is worthless. Many pastors and theologians try to claim that there is disagreement between James and the Apostle Paul, claiming that Paul says that salvation is by faith alone and that James teaches that a person needs to have works to be saved. Actually, Paul and James teach the exact same thing. Paul writes

For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God—not by works, so that no one can boast. For we are God’s workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do (Ephesians 2:8-10).
Both men teach clearly that salvation is through faith, but that faith naturally leads to obeying God and producing good works.

The importance of this is illustrated by the story of the Israelites refusing to go and take the Promised Land (Numbers 13-14). Moses sent 12 spies into the land to see what it was like. All of the spies said the land was great, but ten of them said that they could not take it. They refused to believe God. Joshua and Caleb admitted that the other nations were strong, but they believed that God would give them the victory. The whole nation of Israel chose to agree with the ten spies, choosing not to go into the Promised Land. Their lack of faith in God caused them to choose not to go into the Land. If they had believed, then that belief would have led them to take action and that would have taken over the Promised Land. Even if they did not believe that they were strong enough, they could have trusted God and gone up to take the Land even if they were wetting their pants all the way.

The point of the story is this:
You can say that you believe God all you want, but if it does not move you to action, it means nothing.