Doltologist - Try common bleedin' sense. Much underrated IMHO.
The problem with that is common sense is a heuristic, or rule of thumb. It varies from person to person relative to what part of the world they live in, their upbringing, etc. No sense is truly "common".
There are no short cuts. There are no three sentence or three volume reads a person could read or recite that would convince them in of itself, because of the preconditioned ideas one may already hold to. While it is true that no one is born with theistic belief, the problem is that such belief is usually taught very young in a person's life, and as such, becomes very foundational to the way a person thinks, and filters all other information through. Until they first learn to think critically, trying to undo that belief is likely a wasted effort. You can tell a theist that the burden of proof is on them all you want, (and be right), and still get nowhere. Ever wonder why? Re-read what I just wrote.
My best recommendation would be to take a class in logic or critical thinking first, if someone really wanted to speed up the process. As a non-linear thinker, I tend to learn a bit differently than some, so through considering a lot of information about many subjects, I was able to draw an atheistic conclusion. Your mileage may vary, and who knows, you may come to the conclusion sooner.
d4g