Real faith is more than just knowing or even believing that something is true. After all, even the demons are perfect monotheists. Real faith means counting on it. It means that this faith becomes a real factor in life, decisions, actions. Faith - trust - is not something that can be put on one side of life in general, so that it occupies a more or less watertight compartment. In so far as it is real, faith becomes a factor in life and shapes everything around it.
Isn't this what Abraham found as he climbed the bitter slope of Moriah?
-Hey, Abraham, do you believe that God can raise the dead?
What would he have said as he bound his son - his only son, whom he loved - to the altar they had built together?
-Believe it? I'm counting on it!
That is why faith will always have more than a hint of desperation about it. Faith actively eschews - despairs of - other more obvious, more ethical, more strategic, more sensible ways of getting things done. It walks away from them, because faith is counting on something else - the power and promise of God.
That is why faith is not just believing, for example, that God answers prayer. Faith is counting on God's promise to answer, and that means venturing something. Putting it all in his hands. Faith is putting yourself in a position from which if God proves false to his promises, or lacks power, or will not move... then you will fall. It is the precipice, and yet at the same time it is the road. Immense daring, and yet also just ordinary life. Dangerous, but absolutely safe.
Perhaps one of the greatest ironies of the life of faith is that so much of it simply involves counting on God to be faithful to me even when I don't count on him. That looks like the prayer of repentance, the perseverance in getting up and rededicating ourselves to his service every day even though we failed yesterday and will fail again today. Neither so terrible nor so rewarding as Moriah - but I guess Abraham had plenty of those days too.
Faith always shows itself in works - works that make no sense without faith - just because that is what trust means. It means acting as if the Other Person is trustworthy.