What I may believe at one time is likely to change. It seems to me that there would be something wrong if my beliefs didn't change as I learn more.
In my search for truth, I've realized that many things I believe are founded on a series of other beliefs... If one of those founding beliefs change then all beliefs based on that belief may be shaken.
I've found that part of search for truth is about weeding out false beliefs. For example, before the "millennium year," 2000 I heard a lot of talk about world chaos and disaster. I didn't believe full heartedly (without other beliefs contradicting the belief), but I did believe somewhat heavily that something catastrophic was going to happen. In a large part needless to say, that changed rather suddenly when the year 2000 came and no catastrophe happened. I was not really saddened by it not happening, but I was shocked, because I had put so much time and taken for granite (though not quite diamond) that belief, that my grasp on reality was shaken.
Perhaps that's where my spiritual life was re-sparked, especially because my assumptions of the year 2000 problem were largely religious. What I learned from this was the religious views I held were wrong, the mass hysteria of the time that drew me in (so I should look out for that kind of thing in the future), and now I look back and realize my grasp on reality was shaken so badly due to losing my belief...
My point is, that although I tend to no longer put a lot of faith in many founding beliefs, those beliefs that I do have are constantly being molded. Sometimes time by itself disproves beliefs, while usually there are other beliefs that I'm testing.
What do I believe? That which currently seems most true to me. Sometimes there's a tie. Sometimes two things are believed "possible" that may even directly contradict each other.