Whatever God requires is right

The Prophet Joseph Smith taught that it is the Lord who sets the standard of right and wrong: “God said, ‘Thou shalt not kill’ [Exodus 20:13]; at another time He said ‘Thou shalt utterly destroy’ [Deuteronomy 20:17]. This is the principle on which the government of heaven is conducted—by revelation adapted to the circumstances in which the children of the kingdom are placed. Whatever God requires is right, no matter what it is, although we may not see the reason thereof till long after the events transpire. If we seek first the kingdom of God, all good things will be added” (in History of the Church, 5:135).