Doubting/Believing

In my writing class, we got the assignment to write a doubting and believing paper. This is different from a regular persuasive essay because it is only allowed to use one source, on the doubting side, so it really has to be just opinion.

I was thinking about writing about whether or not evil exists, but I don't know which side would be doubting and which would be believing.

I think I'm going to write about how bad it is to push your own opinions onto other people (religious fervor-door-to-door Jehovah's Witnesses, the Crusades, Jihads, US foreign policy, etc.)

I don't really know how I'm going to argue against myself yet.

Any thoughts are appreciated.