Re: Atheist parents?
DH and I are atheists and scientists, so we have little patience or room in our lives for religion of any sorts. His parents are also atheists, while my parents probably are (they don't talk about religion or go to church.) Bullying was never an issue, and religion rarely came up in school (public school.) On one occasion, a christian girl was going around telling kids they were going to hell, while she was going to heaven to wear a crown; she got suspended for 3 days and it never happened again.
We still celebrate Christmas and Easter, since who doesn't love Santa and the Easter bunny, and all that holiday food, but there is never any mention of god or religion. We do take ethics very seriously and discuss that with DH, but I don't feel the need to explain religion or expose DS to it. Religion just seems crazy to us, and we would prefer to teach him about science and fact.