There is a vast difference between "trust" and "faith", although we often confuse them. Trust is built by a process, by experience; we trust people only on the basis of recent past behavior. "Trust" on any other basis is an illusion. "Faith", on the other hand, is a decision. It is an act of the will, like love. You cannot gather enough evidence to prove (or disprove) it. Of its very nature, faith is based on what we cannot know empirically. As usual, greek is much clearer about this than english is. It actually used different words to express these different ideas. the greek verb ginoskeo (γινοσκεο) means "to know", but it implies knowlege gained through experience...it is a relational word more than an intellectual one. Pisteo (πιστεο) is "to have faith" or "to believe", often with no extensive experience to substantiate the belief. This is the topic of Hebrews 11, and the examples that follow it display this clearly. There are still other words in greek that further subdivide the meaning "to know" into other specific catagories of knowlege.
Both trust and faith require a decision from us, and both must be maintained in some way. Certainly there is intentionality in both. When we're not intentional about the process behind building trust, the problem is not usually that we don't trust anyone...it's that we trust everyone. This is an unbalanced and unstable situation that has a tendency to lead us to disappointment and cynicism. interestingly, when we're not intentional with faith, the opposite thing happens. We wait and wait, searching for more and more evidence, and when nothing happens (because we're missing the point), we become more and more sure that there's nothing to have faith in. There's nothing more frustrating than to not be trusted by someone against all evidence to the contrary. I see it in relationships more frequently than I'd like. As the result of bad past experience, one partner simply refuses to take the final step and trust the other, no matter how faithful the other has been. The hard part is, no matter how much counselling they get, the essential "fix" never changes...he/she will eventually have to take the step into trust. We can make it easier perhaps by dealing with the reasons why trust is so difficult, but we can't change the solution.
Someone at the Mission made this comment today: "I don't feel bad about not wanting to trust God...what I feel bad about is that He can't trust me." I had to think about that one for a while. Does God "trust" me? What does that mean in the context of my fallenness? I think the answer is that it's a meaningless question. God is infinite; God is perfect and sinless..."trust" on those terms would require me to be the same. Jesus already paid that penalty for the fact that I'm not, and never will be. He doesn't have to trust me. Paul makes it clear in Romans that that doesn't give us license to do whatever we want, "that grace may abound", but it does allow us to take a deep breath and be truly "sure of the things hoped for..." (Heb 11:1).