Faith in many quarters these days is in sad repair. To the skeptic (and more) faith means believing something when you have no reason to believe it. They buy the Archie Bunker version: "Faith is something you believe that nobody in his right mind would believe." It's something you believe in spite of the evidence. Something you believe even though there is no evidence. Even Mark Twain said, "Faith is believing something you know ain't true." Richard Dawkins called it "one of the world's great evils."
Skeptics aren't the only ones. Some have said, "You must believe in your heart, not in your mind." Many in favor of "faith" are convinced that if there is evidence, it isn't faith. If you have reasons, it's not faith. It is far better to believe without reason, to "believe in your heart, not in your mind."
The Reformers defined biblical faith as a three-part structure. They called them notitia, assensus, and fiducia (because, of course, they couldn't speak plain English! ... Come on, Reformers!). The first refers to the components, the facts. "George Washington was the first president of the United States." Facts. The second refers to "assent". We agree with the truth. It is mental assent. Many think this is the end of faith. Mental agreement. While it is necessary, it is not the final component. The final piece is fiducia -- conviction. It is when the truth (notitia) that we assent to (assensus) produces conviction upon which we act (fiducia). "Is that a chair?" "Yes." (notitia) "Do you believe that chair can hold your weight?" "Yes." (assensus) "Will you sit in it?" "Yes." (fiducia)
All three components are necessary. You have to have facts. Basing faith on that which isn't true will accomplish nothing. You have to believe the facts. Failing to believe is not biblical faith. It's not biblical faith without believing the facts. That is, if we either fail to believe the truth or what we believe is not the truth, it's not biblical faith.
That final element is key. I may be perfectly accurate in stating that George Washington was the first president. I may believe that fact completely. This does not mean that I have faith in George Washington. I may be correct in calling that a chair. I may assent that it will hold my weight. But I don't have faith in that chair until I sit in it. Or, as James put it, "Faith if it has no works is dead, being alone" (James 2:17). Faith, then, causes action. It is what you do as much as what you believe.
The skeptics are wrong. Biblical faith means literally to be convinced. It includes evidence and reason. It is not in spite of them. And those who argue that you have to "believe in your heart" and not in your head are wrong. Both the truth and our mental assent to the truth are fundamental to biblical faith. Faith, then, takes all the evidence and all the arguments and pushes you to act on it, to take the next step, to go to the conclusion you can't see because of the evidence you do see. Faith changes minds, changes hearts, changes lives. You will always act on true faith. That's its nature.