Let’s start with a rather basic word, with the more technical terms to come later. If there are particular words that readers puzzle over, I would be pleased to hear about them so that they can be included in my glossary of the Christian fait…er…religion.
Of course, the previous sentence could have been completed with “faith,” as the 3rd definition in the Oxford Dictionary is “a system of religious belief,” but this is not what faith means in the Bible, nor is it what this preacher means when it is spoken in church. Of the remaining two definitions, 1) “complete trust or confidence,” and 2) “strong belief based on spiritual apprehension rather than proof,” most religious people probably would settle on the 2nd. This is because faith, in a religious context, tends to be associated with belief, but neither is this what the Bible means by faith.
The Oxford Dictionary properly lists “complete trust” as the first definition. In fact, it is not even necessary to use an object with faith, that is, it is not necessary to have faith (or trust) in anything. Simply “faith” will do.
I would define faith as the attitude necessary to step into a completely unknown future with confidence, except 
that this definition could also apply to naivety or foolishness. But faith is neither naïve nor foolish, because it has a firm, rational footing in one’s experiences that will have provided a basis for having faith. Ironically, these foundational experiences may well have come from risks naively or foolishly taken, but which gave positive outcomes. Risk, of course, when not taken naively or foolishly, involves fear; faith is the antidote to such fear.
There are two ways people meet fear. One is to have faith and the other is to diminish the risk with certainty. If one can reduce the risk with knowledge, one may act with relative safety. The manned mission to the moon was a risk that required faith on the part of the astronauts, to be sure, but the risks were reduced to a manageable degree with huge amounts of knowledge. This is what those who demand certainty from their belief system are after, too, except that in matters of G-O-D, there is no absolute knowledge; there is only faith. To be so certain of beliefs about G-O-D that they must be held firmly against all evidence to the contrary is not, as is often presented, to be faithful; it is quite the opposite, because it is an attempt use knowledge (pseudo-knowledge) to find courage rather than faith.
Marcus Borg and John Dominick Crossan, in their book, The First Paul, define faith as “total commitment,” which I understand as giving oneself or opening oneself to something beyond one’s self. In the context of Christianity, this means opening oneself to the grace of God and all that this brings. “Grace” is another one of those jargon words, which I will explore next, but for now, let us just consider that God offers all the necessities for “eternal life” (another jargon term to be explored) , but that we can only appropriate them with faith, i.e. our openness, our commitment.