The most simple [example of a tautology]? circular reasoning:
God exists because this book says it does.
This book is special because God inspired it.
Or another big one: God is good no matter what. If something good happens, praise to God. If something bad happens "he moves in mysterious ways and who are we to read his mind".
I don't usually bother with atheists, but
1. A circular argument is not an example of a tautology (read the dictionary), but I suspect that was what you meant in the first place.
2. Your first example is true of religions like Christianity or Islam, but not all religions are based on a book or a single "revelation".
3. In the second argument, again (like most atheists) you are mistaking an argument against Abrahamic religions with one against religion in general. The argument from evil is indeed a very powerful argument against those religions which believe in an omnipotent, omniscient, and omnibenevolent creator. But a creator doesn't have to be any of those. If one who wasn't was challenged, she might reply "I don't claim my universe is perfect: it was just the best I could manage. Sure, some of the inhabitants sometimes get caught in the machinery, but they have a reasonable life the rest of the time. If you don't like it, go and kill yourself."
Paganism is not based on circular argument. People have religious experiences. Those which are weird are usually ignored by others (excepting the Abrahamic "prophets") and so a consensus builds up. The pagan religions of the Americas, Africa, Asia, and Ancient Europe all have a similar world view, independently arrived at. Anyone who thinks that involves circularity needs to study some elementary epistemology.