For those who have not faith:

"And whosoever among you are sick, and have not faith to be healed, but believe, shall be nourished with all tenderness, with herbs and mild food, and that not by the hand of an enemy. And the elders of the church, two or more, shall be called, and shall pray for and lay their hands upon them in my name; and if they die they shall die unto me, and if they live they shall live unto me." (D&C 42:43-44)