If you haven’t read it already, Dan Barker’s book Godless is a fantastic primer. I recommend it for all budding atheists and wish that all Christians would read it! If you’ve ever asked questions about why you should be an atheist, this book will answer all those questions for you. It clearly shows how the Bible is full of errors and discrepancies. Being a former evangelical preacher turned atheist, Dan knows his stuff!
I haven’t read it (probably wouldn’t tell me anything this far in that I don’t already know) but I’ve read various articles and posts by Barker and about his life story and he seems like a very solid and reasonable guy from what I recall. I agree it would be a good read for the newly apostate or those on the fence, as well as for Christians who REALLY IN FACT want to ACTUALLY UNDERSTAND atheism, and can actually LISTEN. All five of them, lol.