had a lot of this myself lately... I went for the "some people think he is, just like some people think its okay to eat meat" approach (we're all vegitarian) I guess the secret is to find some other life choice they can relate to or already understand about.
I think if you dont belive in god yourself, and dont want to activly discourage it in your kids, then thats about the best approach you can take, and its not really a cop out.
Incedently, do you ever wonder about RE teachers these days ? for some reason ours seemed to think thats its okay to hammer home (pun intended) all the jucy details of crucifiction to our 5 year old son... who's now back to sleeping in our bed cos of the nightmares it brought on... cheers very much... but can you imagine how quickly social serices would be round, if he went to school and said i'd let him watch an 18 rated film with the same level of violence?
Our 6 year old ended up having nightmares for weeks after his teacher told him that everybody dies including your parents.