In 1908 in a general conference, President Joseph F. Smith read section 89 of the Doctrine and Covenants—the Word of Wisdom. Then he, both of his counselors, and the President of the Twelve all spoke to the same subject, the Word of Wisdom. Then a vote to accept it as binding upon the members of the Church was unanimously passed.

That revelation begins, “In consequence of evils and designs which do and will exist in the hearts of conspiring men in the last days, I have warned you, and forewarn you, by giving unto you this word of wisdom by revelation” (D&C 89:4).

It is a shield and a protection unto our people, particularly to our youth. It becomes a part of that “whole armor” of God promised in the revelations to protect them from the “fiery darts” of the adversary (see D&C 27:15–18). – Boyd K. Packer, “The Spirit of the Tabernacle,” Ensign (CR) May 2007