No one can make themselves believe something they don't believe. And why should they be expected to?

But it's not just a question of to believe...or not believe. It's a question of:

1. Do I believe this?
2. Do I not believe it?
3. Do I simply not know for sure?

If it's # 3, which is most often the case, then it isn't a question of believing or not believing, it's a question of:

1. Does this seem likely to me?
2. Does it seem unlikely?
3. Does it seem moderately likely or unlikely?
4. Is it possible that I need a lot more information about this before I can even have any justification for having any strong opinion about it?
5. Is it possible that I don't know much about this yet?
6. Is it possible that somebody knows more about it than I do?
7. Is it possible that I don't yet have ALL the answers? ;-) !

And if so, what would I base my categorical statement of belief or my categorical statement of non-belief on? A house built on sand?

Why is it that people keep stating absolutes all the time, as in saying "I believe this" or "I don't believe that". How much have they really got to go on? Do they really know?

Not too much to go on in most cases, I'd say. They mostly go on assumptions, based on prior assumptions, based on somebody else's prior assumptions.

It is a bit foolish to always talk in absolutes when the fact is that one really doesn't know.