Here's a definition I'm rolling around in my mind.
Having Faith: projecting knowledge you have gained back onto your past self in time for you to act on that knowledge before you have actually acquired it.
Implicit in this definition is that in order to have faith in something it must actually be true (otherwise the knowledge will never be gained). Oh well. This definition probably doesn't make sense in English.
"The presentation or 'gift' of the Holy Ghost simply confers upon a man the right to receive at any time, when he is worthy of it and desires it, the power and light of truth of the Holy Ghost, although he may often be left to his own spirit and judgment." --Joseph F. Smith (manual, p. 69)
"Inasmuch as ye have done it unto one of the least of these my brethren, ye have done it unto me."