True Belief

What does it mean to believe something? If I say I believe in Christianity, does that make me a Christian? How does that compare to me saying something like, "I believe you're a waiter". And is this the same type of belief as when I say something like, "I don't believe in global warming".
After taking a course in Vipassana meditation, my understanding of belief has changed. Belief in the first case has to be followed up by action. If you say you're a Christian, you need to do something that is Christ like. This point was driven home to me during meditation. If I was to say I am a Buddhist, I would have to meditate and follow the 8 fold path. Just saying I believe in the Buddhist mythology doesn't mean that I'm a Buddhist. The statement "I believe you're a waiter" follows a similar logic. My belief is only true if you are in fact a waiter (you act like a waiter).
How about "I don't believe in global warming." In this case, the truth is impossible to discern by observing for a moment. My personal belief has no bearing on whether global warming is true or not. It's not something I can ask the Earth directly, unlike asking you if you're a waiter. Therefore, our beliefs regarding global warming depend on 'experts'. Scientists and climatologists that research this topic may be able to tell you what they think, but the truth is impossible to discern immediately. The belief only becomes true or false in the future. Scientists never have all of the information, so they could always be wrong. There are always more variables than we can imagine.
Being that we can't know the truth of global warming right now, how should we behave? Should we just pretend it doesn't exist and then change our behaviors if we discover that it is happening? I would argue that we should believe that it is really happening, and act accordingly. Even if the experts are wrong and the trends they see are not indicative of global warming caused by human activity, we have to act as if global warming is actually happening. It's the type of event that can't be solved quickly. When the evidence becomes conclusive, it's probably too late to fix it.
Beliefs are important, because what we believe directly influences our actions. Having true beliefs is preferable, but when the truth is not immediately apparent, believing in what appears to be true until conclusive evidence is presented is preferable. Some things just can't be fixed if we wait too long.