It's unfortunate I only got a handful of replies to what I thought was an interesting question. Nevertheless, this is my opinion:

I believe that the case against adult/child sexual contact, when we take religion out of it, is very weak. We know that such contact is not inherently harmful and that any harm is the result of societal pressure. By the time decriminalization could occur, societal pressure must have been diminished to the point where it is no longer the major factor it is today, so that's not something we need to consider when discussing decriminalization. As Cat has already stated, parents always trump the law anyway, which means parents are still able to enforce their own moral standards in their household, just like they do regarding countless other topics today. Thus, I am in favor of decriminalizing adult/child sexual contact.