Show creator Barbara Hall wrote a list of guidelines for the writers, which she called "The Ten Commandments of Joan of Arcadia". These "commandments" are:
- 1. God cannot directly intervene.
- 2. Good and evil exist.
- 3. God can never identify one religion as being right.
- 4. The job of every human being is to fulfill his or her true nature.
- 5. Everyone is allowed to say "no" to God, including Joan.
- 6. God is not bound by time. This is a human concept.
- 7. God is not a person and does not possess a human personality.
- 8. God talks to everyone all the time in different ways.
- 9. God's plan is what is good for us, not what is good for him.
- 10. God's purpose for talking to Joan, and everyone, is to get her (us) to recognize the interconnectedness of all things - i.e., you cannot hurt a person without hurting yourself; all of your actions have consequences; God can be found in the smallest actions; God expects us to learn and grow from all our experiences. However, the exact nature of God is a mystery, and the mystery can never be solved.