In my Philosophy of Religion classes at MCCC we study classic and contemporary arguments both for the existence of God and against the existence of God. If one wanted to dig deeper into atheistic reasoning, how would one go about it? Here are some suggestions.
1. Pick up a good philosophy of religion anthology. Try this. Here's the text I use for my Philosophy of Religion classes. (Get an older edition used for less $$$.)
2. Read The Evidentialist Argument from Evil, by Daniel Howard-Snyder.
3. Read the debates between prominent atheists and William Lane Craig.
4. Read atheist William Rowe's Philosophy of Religion: An Introduction.
5. Read the debate between William Lane Craig and atheist Walter Sinnott-Armstrong.
6. Forget the neo-atheists Richard Dawkins, Sam Harris, and Christopher Hitchens.