By this I mean, what does the Bible say faith is, and what it entails?
Faith is belief that comes from hearing or reading the testimony of others. I have never seen Paris, New York City, or Beijing, but I have faith that they exist because I have read about them from reliable sources. Faith is also, more broadly, the foundation of our hope as Christians. Because of our belief in the testimony of those long past, written for us in the Bible, we have hope and look forward to the fulfillment of its promises. (Heb. 11:1, paraphrased)
Hebrews 11 gives us a picture of what faithful men did because of their faith.
By faith, Abel offered a more excellent sacrifice than Cain.
By faith, Noah prepared the ark.
By faith, Abraham went left home without knowing where he was going, dwelt there as a foreigner, sacrificed his son.
So, Biblical faith is faith which causes obedience to God.
James 2:14-26 says, "What does it profit, my brethren, if someone says he has faith but does not have works? Can faith save him? If a brother or sister is naked and destitute of daily food, and one of you says to them, 'Depart in peace, be warmed and filled,' but you do not give them the things which are needed for the body, what does it profit? Thus also faith by itself, if it does not have works, is dead.
But someone will say, 'You have faith, and I have works.' Show me your faith without your works, and I will show you my faith by my works. You believe that there is one God. You do well. Even the demons believe—and tremble! But do you want to know, O foolish man, that faith without works is dead? Was not Abraham our father justified by works when he offered Isaac his son on the altar? Do you see that faith was working together with his works, and by works faith was made perfect? And the Scripture was fulfilled which says, 'Abraham believed God, and it was accounted to him for righteousness.' And he was called the friend of God. You see then that a man is justified by works, and not by faith only.
Likewise, was not Rahab the harlot also justified by works when she received the messengers and sent them out another way?
For as the body without the spirit is dead, so faith without works is dead also."
So what do we learn by these passages about faith? We must believe, we must obey, and we must do good works, all to have a faith that saves us. Notice that belief is not enough. No one professing to be a Christian believes that the demons are saved, but even they believe that Jesus is the Son of God! Many say this is enough to save someone, but this passage directly refutes that!
Faith and obedience are inextricably linked. But so many say that only faith is required. Should we believe God or men? Must we obey as well as believe to be saved from our sins?
