Instead of the usual Fun Fact/Question of the Day, give the children a joke to which they can respond. Critical thinking about the subject as a whole can lead to very interesting and humorous responses.
Atheism, Religion, God is Imaginary, Satan, The Devil, Humor. Man, if Satan ever starts losing his hair there will be hell toupée. I think this may actually be the worst pun of all time. Congratulations. You spelled "best" wrong.