I can see the reasonableness of say Tennesee's 4 year difference* because it would be a shame to have a young person life ruined by a too ridged law reguarding age while you are just getting used to these new feelings and what not.
In Michigan the age of consent is 16. There is no similar age clause. Two 15 year olds are breaking the consent law. That is bad for the kid who turns 16 and gets prosecuted for being with his under 16 girl or boyfriend.
I am a theist, but even I couldn't believe Richard Dawkins would say something like the thread title. Though, I believe he is mistaken that he wasn't harmed permanently from what happened to him. You can get counseling, but it it always with you and it always affects you. It is weaved into the fabric of your being.
The irony of course is that many theist organizations seem to be the breeding grounds and playground for pedophiles.
Any place you have children, you will find adults who prey on children, young teens and older teens for sexual gratification. Churches, synagogues and the like are no exception. Police and medical workers, caretakers are always getting busted for child molestation and pornography. What does the organization or school do about it, when it is discovered, is what's key.