We introduced DS to greek and roman mythology first. Being a nonreligous house, he was getting a lot of mixed messages at school and confusion about who was doing what and why. So we started with mythology and creation myths from other periods and cultures. We've touched on Christianity briefly but not a lot.

You may also find some answers in "Parenting Beyond Belief" as it talks a lot about how to raise moral, ethical children outside of a religious upbringing.