Wow, what a tough question. One thing Richard Dawkins has always professed is that telling a child they must believe something is wrong--however, I also think a child should have access to all religious beliefs in some way, so they can make the decision themselves when they're ready. The scary thing about this is whether or not the brainwashing of religious institutions is coming into play. I think as a parent, the most important thing is the welfare of your child, no matter your belief. If you want your child to be exposed to different religions, as well as atheism, I think you should ask yourself is an organization based on creationism is the best place to do that. If you think Scouts is an important factor, maybe try to find a way to expose him to other mindsets on the side. I really think the most important thing in this situation is to make sure he has all the resources he needs to make the decision HE wants when he's ready. I hope you find the right answer, and I wish you the best of luck.
Chris Roth
http://thereligiousfallacy.wordpress.com/
http://thereligiousfallacy.wordpress.com/