The Church must be cleansed, and I proclaim against all iniquity. A man is saved no faster than he gets knowledge, for if he does not get knowledge, he will be brought into captivity by some evil power in the other world, as evil spirits will have more knowledge, and consequently more power than many men who are on the earth. Hence it needs revelation to assist us, and give us knowledge of the things of God.
(Joseph Smith, Teachings of the Prophet Joseph Smith, p. 217)