"Now faith is the substance of things hoped for, the evidence of things not seen."
-- Hebrews 11:1
So, what can we see about faith in this verse?
First,
faith is now. It says "Now faith is". There is some debate over whether or not the word "now" was actually in the original Greek text. So, let's say that it wasn't. That leaves us with "Faith is..." The last time I checked, the word "is" is present tense. So, even without the word "now" faith is still obviously rooted in the present.
Why is this important? Because a lot of people believe that God will fulfill their needs and desires some day -- even if it's only in the sweet by and by. So, here's our problem: if we believe that God will answer our prayers at some point in the future, then when we use our faith to pray, we are putting the answer off into the future.
Let me see if I can explain this a little better. If you believe that tomorrow God will answer your prayer, and tomorrow never comes (because it's always today), then when will you receive your answer?
If this is still a bit muddy, take a look at this scripture from Mark: