My MIL is JW and explained to me why she door knocks (I hate it and don't agree with it so it's hard for me to accept this part of her faith)... it's because in the bible there is a line that says something about "spread the word to your neighbours" so they really do feel that they are not following God if they neglect this part.

With regards to religion, I grew up in a non-religious household too and when old enough (grade 4) I said I didn't want to do religious classes at school anymore. At that time Christian education was still aprt of the public school system. My school didn't know what to do with me and let me hang out doing not much with a teacher in the room... soon more children joined me once people realised they had a choice. We then started a class called 'religions of the world' and we learnt about a new one each week. I loved it as it was teaching about diversity without ramming beliefs down my throat. Maybe your son would really enjoy attending the different religious classes- I'd talk to him about it.