Faith is being sure of what we hope for and certain of what we do not see.
Notice a few things about this verse (Hebrews 11:1)
1. It is being sure. (of what we hope for). From where does this surity come? The verse says what faith is (being sure) but not where faith or the surity comes from. As I see it, the surity can come from two possible sources, namely god, or our own mind.
If surity comes from god, why does he constantly encourage us to "have faith"? We shouldn't need to strive to have faith if it is truly a gift from him, installed in each of us at the factory so to speak. An apologetic would at this point say something like, the fall of man in the garden of eden took away our ability to have faith. This is not what the bible says. The bible says we ate of the tree of the knowledge of good and evil and thus attained the knowledge of good and evil and became as god themselves (no that's not a misprint, the bible says, man has become as US, this is god speaking). It says nothing of the ability to have faith, unless you interpret faith to be ignorance of the world around us. If that's the case then, as ignorance equals faith, then we did lose our ability to have faith in the garden. However, faith is not defined by the bible as ignorance, it is defined as being convinced of something.
If the surity does not however come from god, then it must come from ourselves, which is of course where it does come from. We can certainly have faith in something. The idea of faith is a very noble one. For instance, I can have faith that my wife will not cheat on me. This is a certainty that has come most assuredly from myself. I chose to believe the promise she made to me when we got married. It most certainly did not come from god.
2. Notice something else about the next phrase of this verse, "of what we hope for". Now this is simply too easy. Wishful thinking! Just because we hope for something to be the case does not in any way make it actually be the case. I can be absolutely sure that I will win the lottery one day, but as we all know, the likelihood of my being able to retire on my winnings is, well......
3. The next phrase says " certain of what we do not see". This is an interestingly misunderstood phrase. If we do not see something but are yet certain of it's existence, then according tio this phrase, we have faith in it.
It in no way states that if we do infact see something and choose to disbelieve it, that we are exhibiting faith in anything.
Again, Faith is not the disbelief of the observed. In this way, I find the christian's argument against evolution on the grounds of their faith in creation to be inapplicable. Faith in the story of creation translates into being certain of the story of creation even though we don't see it. This is in complete contradiction to the observed phenomenon of evolution through natural selection.
The bible however, is conspicuously mute on the subject of when faith in the unseen and beliefin the observed butt heads. It seems to me that god, if he were truly all-knowing, would have seen this coming and given instructions as to how to get around this conundrum. Alas, no such luck. God most certainly is a figment of our deepest fear-driven imaginations and the feeble attempt by the organized christian church to perpetuate the stupidity of the bible hopefully will one day be eradicated by reasonable, rational minds.