I just glanced through it and it's not too bad. The statement they make toward the end about the RC church saving Jews conveniently ignores the fact that Hitler's first treaty was with the Vatican, that he himself was catholic, and that the few Jews saved by the church could have been far greater had Pius XII been more vocal. Should we also mention that catholic dogma held that the Jews killed Jesus until Vatican II didn't help the Jews' plight back then.
So far as I'm concerned, ANY positive action taken by the RC church is far outweighed by the perfidies it has committed over the centuries.
At first thought, I can't say that I'm overly keen on the "Indian Jones" look - although that's more of a personal view. However, it does apply some "fire and brimstone" which really it out of place in a book about, er, lack of fire and brimstone.
I've only scanned the text very quickly: but some of your examples are slightly off-base and your sample fallacies are not 100% clear. Try the fallacy files or Nizkor pages.
If you want to make guys shrivel a bit when discussing the female genitalia, it's worth describing that both organs are actually the same one! I won't go into detail here for the more sensitive reader, but you'll see that both develop from the same embryonic bud and therefore, have essentially the same nervous connections. Mutilation of this area is directly akin to having the glans surgically removed with precisely the same effect.
Next, drop the dope references. You might consider hash to be safe but I have several friends (one of whom is only in her mid 20s) all of whom are showing the deleterious effect of cannabis use: memory loss and paranoia being two that spring to mind.
Anal sex likewise is dangerous for the receiving partner: no matter what you do. Our rectum was not designed for that purpose (that's why vaginal tissue is completely different in nature and "design") and while gay men might not have an option (at a pinch) it's not the sort of thing we need to describe in detail in a book about the lack of belief. In fact, this is one area where religion got it right for the wrong reasons.
Don't take the piss so much! Really, you're either writing satirical comedy or you're writing a serious diatribe. The two are not mutually exclusive, but it's best to avoid it when you're trying to give facts.
Science is knowledge based on evidence.
Belief is belief without evidence.
These two statements are intertwine. I might say that I believe that the universe began at Big Bang but as soon as I do, those prone to tripwires will jump on me and say that "AH, you believe, you have faith!" and so on.
Atheism IS a belief if is held without evidence! If you believe there is no go simply because I tell you so then you're no better than the pope or any other religious figure.
In fact, all atheists (proper ones, as I call them) are actually agnostics - but we're so close to atheism that it makes no odds; and agnostic sounds a bit wooly and fence sitting even when it isn't.
Atheism comes from knowledge, critical thinking and unbound understanding. It comes from following the facts down whatever path they might lead - even when the answers might hurt or upset us.
My ex-wife has a problem like this - she cannot face up to things that hurt her; even if she cannot change them. Sometimes, we have no option and even now I'm battling to get through to her that you have to accept some things (grass is green, the sea is wet) just because we don't have the power to change them - no matter how strong our will is. I'm actually concerned for her mental health and that of my middle daughter (who suffers with Asperger's and clinical depression) because she simply cannot cope and won't accept the help she needs to move on.
Anyway, that should give you some points to chew on - it's a good book and a great idea.