Can someone point me to another dimension?

[Lestat]

This post will give away my lack of education, but here goes..

As I understand it; There is up, down, left, right, back, and forth to make up our 3 spacial dimensions. And of course, there is also time. Do we know of any other dimensions?

So why is it that I cannot conceive of any other dimension? I mean, I can't even get close! Could a guy who lives on a 2 dimensional piece of paper conceive of the 3rd dimension depth? I honestly don't know.

Has any other dimension been proved? I know string theory relies heavily on multiple dimensions, but as I understand things this is the exact problem with string theory. It is completely untestable and likely never will be.

So my question is, why is believing in dimensions any different from believing in God or religion? I'm SURE this is a dumb question, but I don't know the answer. The string theorists will say that many things point to the existence of these unseen, unprovable dimensions. But the theist will say the same things about religion and God.

Can anyone explain this to me?