I'm trying to understand what people mean when they say that they believe something.

If you drop an object you might express your expectation that it would fall to the ground as a belief. Such a belief is based on a life time of experience. The evidence of your experience leads you to deduce that what has happen previously in similar circumstances is likely to occur again. For less familiar physical phenomena you would test, by repeating actions, just how something works. This is hypothesis and theory as belief.

A different kind of belief might be trusting in people. Suppose that a friend recounts an incident he witnessed to you. You accept that what he is describing as an accurate account of what happened - you believe him. Because you know and trust him you don't need evidence of what he is describing. However you are aware that no matter how objectively he tries to describe the incident to you he may be putting his own interpretation on events, people usually do. You are also aware that, although you trust your friend, the possibility exists that he might be lying to you.

If you later came across some evidence that was incompatible with what your friend had said you would begin to doubt him. If such evidence came from several sources, although you might want to believe your friend, the awareness that he could be lying to you would grow into a suspicion that he was lying to you.

This kind of belief is a little more than accepting things as probably true; there is also an element of wanting to believe your friend and giving him the benefit of the doubt in the face of evidence to the contrary. After all life would be pretty grim if we couldn't trust our friends and we don't want life to be grim. If enough people betrayed us we might become cynical and trust no one.

Neither of these kinds of belief are the same as religious belief. I think that when someone subscribes to a religious belief the desire for the religion to be true, for there to be something that makes complete sense of life, far outweighs their willingness to apply the criteria of evidence. People who base their lives on belief occasionally move from one religion to another, they want something to believe in and cannot tolerate the vacuum of non-belief. Religious belief 'trumps' evidence because the desire for the belief to be true is more important to the believer than reason.

I don't think that belief is a choice. We are all situated somewhere on a spectrum from absolute scepticism to deep religious faith. The sceptic cannot believe anything wholeheartedly without conclusive evidence, the faithful have little interest in evidence because proof does not define their existence as much as belief.