I believe that many if not all religions have a holy/wise book or a legend that guides the people to be good. Good in the sense of being moral, honest, not a thief and not killing. So this holy/wise/legend book encourages the person to be good but the book and the god/prophet that has enlightened the person who wrote the book is needed because some people would not be good without a god/law that requires it of them. So all religions encourage the good in people and this encouragement of good in people can be called the Power of Good. Whether it be a god or just the innate need to be good that encouraged it.