If you ask a group of people what 'faith' is, you will get a collection of different answers. Most of them will be ill-defined.
The concept of faith is central to most religions, but the term is also regularly used outside of a religious context. Despite the pervasiveness of the idea and frequent use of the word, it's difficult to describe what we mean when we speak of faith. For myself, it seemed necessary that discover what the concept of faith is, to better understand my Christian beliefs. What follows is the best description I can offer for the idea of faith.
Everyone acts on faith. The only question is what you have faith in.
To understand faith, we must first start with the concept of knowledge. What is it possible for us actually to know? We can know a collection of facts and occurrences, but we are not able to know exactly how they fit together. We make conjectures about how they fit together, conjectures about causation, be we can't actually know.
A quick example can better demonstrate the point I'm getting at. Let's say I hold a ball. When I let go of the ball, it falls to the floor. It falls to the floor every single time I let go of the ball. From that collection of facts, we can make all sorts of conjectures about gravity and the likelihood that the ball will fall every time that I drop it. But we can't actually know that gravity exists. It's just a concept that we believe exists because it explains so many collections of facts. And it may well be that it does exist, but we just can't know for sure.
It may be tempting to suggest that experimentation can "prove" the existence of gravity. But an experiment just creates another collection of facts. Because all we can know are these collections of facts, we can't actually know that the ball will fall every single time I let it go. Even though it falls every time I've dropped it in the past, and even though there seems to be a high likelihood that gravity exists, we have no collection of facts about gravity itself. Even an experiment is still a collection of facts regarding objects and their movement.
What we have, then, is knowledge of anecdotes, and a collection of anecdotes is what we call data, but we don't have knowledge of causality. Our ideas about causality are always conjectures. Highly informed conjectures, but conjectures nonetheless.
Despite this lack of real knowledge regarding causality, we continue to take actions with the expectation of particular results. I expect the ball to fall when I let it go. But even so, when we act, we don't have a certainty of the results. There is a risk that the unexpected may happen. It is possible that the results of experiments, or larger collections of facts, make us more comfortable with taking specific actions. They may lower the actual risk inherent in the action, or at least the perceived risk. Still, where exact certainty can't exist, some risk remains.
It is at this point that faith enters into the conversation. There is a gap between our knowledge and actions. Faith is what fills that gap. When I drop the ball with the expectation that it will fall, that is an act of faith. I have faith, more easily held by my knowledge of collections of facts and the sound reasoning in favor of the existence of gravity, that the ball will indeed fall.
We all act on faith throughout our entire day. Every action we make is an act of faith that's informed by our experience and knowledge. But we also do the reverse.
We don't take certain actions because we don't believe they will work. Most of us don't have faith that we will fly if we leap off of a skyscraper. Based on the collection of facts we have, that seems unlikely to work, and our faith isn't strong enough to bridge that gap to lead us to take action. That's probably for the best.
As you can see, this means we have faith in certain things and not in others. So the principal concern is where we have faith. In what instances will we have enough faith to bridge the gap and take action despite our uncertainty?
Here the religious perspective becomes interesting. For me, Christianity enters the equation. What is the Bible saying when it encourages Christians to "have faith?" It is about action. It is addressing our lack of certainty about the existence of God and the salvation of Jesus. It is telling us we can take actions in life as though we were fully sure of those things. When I let go of the ball and expect it to fall, I'm acting with a level of expectation that a certain result will happen. When the Bible speaks of faith, it is telling me that I should act with a similar degree of expectation regarding spiritual matters. I should live as though I am certain of everything regarding these Christian issues.
It's only from this perspective that I was able to begin to fully grasp what the Bible is saying about the subject of faith. The Bible's description of faith is a call to bridge the gap to action.