Faith is simply your reliance on work already done.  Consider that you are building a house, or (if that’s a bit ambitious for you) a piece of furniture.  You have designed it on paper over the past several days, carefully diagramming and plotting, determining what pieces you will need, the dimensions of each piece, and how the pieces will be fitted together.  Now finds you at the mitre saw, ready to cut beam D-7 to a length of 38 and seven eighths inches in accordance with the notes you have made for yourself.  The timber is placed, the saw is spinning.  Before you pull that handle, before you sink that blade into the wood and make a cut you can never unmake, are you going to redo all of your design work to ensure that 38 and 7/8ths inches is the correct length for beam D-7?  Well, it all depends on how much faith you have in your design and notes, but the fact is that, while you might have time to measure twice (or thrice), you cannot recapitulate the entirety of your design work before every cut with a saw and every hammering of a nail.  If you do, you’ll never finish your construction.  At some point, you must have some faith in yourself, or in whoever produced your design and instructions if you did not.

This is all that it means to have faith.  Obviously, in light of this, the idea that faith and reason are somehow at odds is not only incorrect but a nonsensical position.  Faith can extend only from reason.  When you make a cut of a board without redoing all of your work to calculate the correct length for that board, you are having faith in your past design work.  That faith is based on the reasoned assessment that the design work.  You can reason this based on your knowledge of your own logical, mathematical, and geometric prowess, on the strength of the proofs and tests you applied to the work (for instance, in determining the length of a diagonal support, both measuring its length in a diagram drawn to scale and calculating its length by Pythagorean theorem—and in so doing taking on faith that Pythagorean law still holds), and on the success of your past designs which have been put to the test of building.  The past work was reasonable—i.e., the product of a logically sound, even scientific process—and your reliance on that work is reasonable—i.e., logically supportable.

Indeed, it would be unreasonable under these circumstances not to have faith, and faith, if you think about it, is not all that “big” a thing.  It takes no great effort of will, no great act of transcendental heroism, to reasonably say, “Based on all of my past work, and all that I know about my past work, it is logical to presume that 38 and 7/8ths inches is the correct length for this beam,” and make the cut.  Faith is not a leap, but the tiniest little hop at the end of a long trudge.  Faith is that tiny bit of trust you have that, since you last proved a thing true, the universe has not gone topsy turvy and made it untrue between then and the moment in which you need to act on that thing.

And there’s the key:  When we talk about logic, reason, science, etc., as applied to our lives, we’re actually talking about a two-stage process.  There is the process of determining what’s true, and then the separate process, which usually takes place at a later date, of acting on that truth.  I can prove that my parachute is sound through inspection, but no matter how temporally close that inspection is to my jump—even if I complete the inspection and repack the ‘chute mere microseconds before I step out of the airplane, there is still a temporal gap.  I must have faith that what I proved true microseconds earlier, is still true.  We could even define faith this way.  Faith is the bridging of the temporal gap between the determination of a truth and the acting on that truth, by means of a meta-logical assessment that that which was logical, or logically proved to be true, remains logical, or true, when the time comes to apply it.  What effort is this compared to all the effort of determining that a thing should be done and all the effort of doing it?  It takes time, attention, skill, and energy to inspect and pack a parachute.  It takes time, attention, skill, energy, and discipline to overcome one’s fear to jump and then actually make the descent, positioning the body properly in the air, executing the free-fall, deploying the parachute at the correct altitude, manipulating it correctly, and performing a correct parachute landing.  The actual act of faith involved, choosing to trust that what was true a moment ago—that the parachute is sound, that the procedures are sound—will still be true after you jump, is pretty trivial.  1% of the work, at best, and requiring no particular leap.

(We must not confuse the act of faith—trusting that what we have already proven to be true is still true and hasn’t ceased to be true just because we’re suddenly faced with the consequences of it if we’re wrong—with the act of courage.  Faith is a logical process distinct from the act of courage it takes to jump.  One might have absolute faith in all of these truths, might be absolutely convinced of them, and still fail to overcome one’s animal aversion to stepping through that hatch.)

Why, then, do we assign such philosophical weight, such grandeur, to the notion of faith, if in the grand scheme of our behavior it is really the least ingredient in any given logical action?  First, because faith is so often bound up with courage that we can easily conflate the two, and second, because the consequences of failed logical process are sometimes as dire as a failed sky-dive or worse.  Courage is the process of acting despite one’s fear, and fear is a reaction to perceived risk (that is, perceived product of the likelihood and severity of potential mishap on a course of action, independent of any assessment of the rewards of that course of action).  One mitigates risk by means of control actions, for instance mitigates the risk of plunging to one’s death by the wearing of a parachute, and mitigates the risk of a parachute failure by conducting a parachute inspection and carrying a back-up parachute.  This is where the faith comes in: we have faith that our past effort at building controls will mitigate the risks we are about to undertake.  The residual risk we face with courage.  Thus, while they are not the same, the faith and the courage have very closely, intimately intertwined roles in facing risk.  Furthermore, as one’s assessment of risk (and thus one’s fear) is dependent on the product of likelihood and severity of mishap, a small likelihood by itself is not enough to alleviate one’s fear.  If the potential severity of mishap is lethal, or equally hideous, then even a very unlikely risk can instill great fear and require great courage.  If the potential severity of mishap is lethal, then one may have faith in one’s prior work to control risk because the likelihood that that prior work is invalid is very low (“I just inspected this chute before we launched, and to my knowledge nothing has happened or could have happened to invalidate the results of that inspection…”), yet one may still find oneself very afraid because the potential severity is so great (“…but what if something, against all odds, has happened between that inspection and now?”).  When the stakes are this high, when the fear is this great, it takes courage to remain faithful, even to one’s own prior work.  The faith itself is still as logical as ever it was.  We just inspected this parachute two hours ago, and it’s been safely packed away and in our possession ever since.  The likelihood that it has against all odds been stabbed or cut since then without our notice is vanishingly small, and that likelihood does not change whether we’re about to jump with it or not.  It is no less logical to trust that our prior work is still valid, and thus requires no more faith.  What we require, if we are about to jump, is the greater courage to stick by that faith because the potential severity, if we are wrong, is so much greater.  So you see, people speak highly of faith, but if the prior work was logically sound, then it is not the faith that is great, usually, but the courage, and when people speak of an act of extreme faith, usually, they should more accurately be alluding not to the faith but to the courage.

This remains the case with religious faith, and I know you’ve been waiting for me to come to this point.  One’s conclusion that, for instance, God exists, made the universe, sent his only Son to die for our sins, and promises redemption to those that follow him and have faith in him, should be logically grounded.  There is no reason for it not to be.  The stories of the Bible, including its stories of miracles and other patently supernatural events, are not of such events happening to some lone mystic on a mountain, who then returned and told the stories to whatever gullible souls they could convince.  The pivotal events of the Bible, including and especially the events of the synoptic Gospels, occurred in the presence of countless reliable witnesses who gave independent corroborating testimony.  These accounts have never been debunked or even undermined with any credibility.

(A semantic note, for clarity, before we go on:  To say, “I believe in God,” is not to say, “I believe God exists.”  The phrase “believe in” as applied to religious faith arose from admonitions by God and Jesus to His/His adherents not to believe He exists/He is the son of God—for those matters were taken for granted—but to trust that He/He would keep his word.  At all points, when God or Jesus says, “Believe in me,” it is in the sense of, “I have told you I’m going to do something for you; trust that I am capable of keeping my promise and that I will do so.”  The conflation of “belief in God” with “belief that God exists” is a modern error.  One must first grapple with the question of whether or not God exists, or whether or not Jesus existed and existed as described, and then, having answered both of those in the affirmative, one may grapple with whether or not one “believes in” God or Jesus, i.e. one believes that these deities will deliver on their promises.)

Let us take the case of “faith” in Jesus, specifically.  He did not say, “Trust me blindly, I’ll raise you from the dead when you die.”  He said instead, “Look, you all know Lazarus, yes?  You lot buried him in there, so you know beyond a shadow of a doubt that he is stone dead, and you other bunch have been with me continuously for weeks now, so you all can attest that I just got here.  Now, watch me raise this guy from the dead.”  And then he did, or so numerous witnesses attested, and no one, including many very powerful people with very vested interests in proving otherwise, has been able to discount that testimony.  “Now,” he continues, “having seen that I can do this, and that I have done this, and that I have done this several times under different circumstances, you can reasonably trust that I am capable of doing it.  And as I have never gone back on my word to one of you yet, you can reasonably trust that I will keep my word in the future.”  This is all rational and reasonable.  This is the prior work, demonstrated and proved.  The call to faith is the call, when you are facing death, to remember your prior work—of having studied these events and determined, logically and reasonably, that Jesus can and will honor his promise to liberate you from death.  Nothing about the sudden proximity of your own death makes it more likely that your past work in assessing the veracity of Jesus’s claims was invalid.  The only thing that changes as your death nears is that you sense more keenly the consequences if you’re wrong, the possibility that death really is a simple annihilation and a permanent end.  Your fear is a fear of the severity of the thing if you are wrong, not a fear that you are suddenly more likely to be wrong.  The faith, then, in your past work, is the smaller part of the act of facing your death.  The greater part is courage.  The faith is easy: a simple, logical presumption that something previously proved, and which has no reason suddenly to become untrue, is still true.  The hard part is the courage: “Yeah, but what if I was wrong?  I know it’s extremely unlikely, but now that I’m looking into the black pit of death… what if I was wrong?”  And that fear makes you cling to life, perhaps at the expense of your principles or morality.

Likewise with temptation.  Let us say you are faced with a choice between some gratification (sex, maybe, or maybe some more mundane pleasure, like the gratification of being rude and abusive to a subordinate who has failed in his job) and self-denial, and all your prior logical work indicates that you should take the path of self-denial.  The immediacy of the choice doesn’t make the validity of the prior work suddenly less likely.  Rather, the immediacy of the choice increases the immediacy of the potential costs.  With the choice immediately before you, you can see immediately before you what you must give up by taking the path of self-denial.  The faith is easy.  “Yeah, I know I shouldn’t…” you say, a short-hand for, “I’ve thought all this through previously, and I have no reason to believe I was wrong then, so it’s quite easy and logical to have faith in that previous conclusion that I should not do this bad thing…”  What is difficult is the courage to stick by your faith, to do what you have faith that you should do or not do, when faced with the costs of that choice.  In other words, “…but I really want to!”

There are people who lack faith.  These are people who are capable of doing logical work, capable of determining a thing to be true, but who then discard their own work simply because they have not reworked it recently, or who are capable of determining that a person is trustworthy, but who then turn on him and suspect him of treachery just because he has not proven his trustworthiness in the last five minutes.  These meet the definition of “lacking faith,” but we would as easily describe these people as irrational.  If the faith was rationally founded, then abandoning it, reversing or doubting one’s prior logical conclusions or another’s proven nature for no logical reason—indeed, for no reason other than that some time has passed since one last proved it or saw it proved—is a failure of reason, a failure of logicality.  These people exist, but they are not the majority case.  The majority case is just weakness, usually in the form of cowardice.  The majority of people who seem to fail in faith still have faith.  They know and would attest that what they proved before is still true, or that the qualities an ally demonstrated before that ally still possesses, but they act in spite of this knowledge simply because they can’t overcome the inner animal that responds only to present visceral impulses and has no ear for logic.  They act in spite of knowledge they previously determined true and still do believe simply because acting in spite is easier.  Not thinking is easier.  Such a person has every faith that the parachute is still good, that the parachute will save him if he uses it.  He chickens out simply because he chickens out, because even with reasonable faith in his past work, he still can’t overcome the animal.  Such a person has ever faith that the right thing is not to take advantage of her inebriated state and go to bed with her, but he does anyway because he is simply too weak to make his inner animal listen to reason.  Such a person compromises his Christian conviction not because he has lost faith in Jesus to save his soul—he determined previously that Jesus could do this and would do this, and he still believes Jesus could and would—but it’s simply too hard to make the shamed animal ask for it.  So much easier to wallow in self-pity and the pride of being outcast. (Before I close, let me revisit the earlier aside:  The third category of person who is commonly said to lack faith is the person who never believed the founding proposition to begin with.  The person who never believed that the correct length for the beam was 38 and 7/8ths inches, never believed the parachute was sound, never believed Jesus existed or did those things.  In common parlance such people are often described as lacking faith and included in descriptions of the faithless, but this is incorrect thinking.  As the person never did prior work, or never had prior work demonstrated for him, he has nothing in which to place his trust, nothing in which to have faith, therefore he cannot be said to have failed in faith, nor in the courage that is dependent on faith.  This is not a person who fails at the step of “believing in God” but never got to that step, because he never got past the step of believing God exists at all.  Recognize the difference between problems of ignorance and problems of faith or courage.  A person must be educated and empowered to perform a logical process, and must perform it and come to a logical conclusion, before that person can even be said to have had an opportunity to engage in faith.)