This is a pretty all-encompassing statement. All actions, it implies, are influenced by the two great governing forces in the universe. It must be frustrating for the do-gooder atheist to finally discover that his actions were inspired by the Lord. The light of Christ fills every heart. Therefore, one who does good by this light is, in fact, acting as an instrument in the Lord's hands, for light and truth forsake that evil one (DC 93:37). For behold the Spirit of Christ is given to every man, that he may know good from evil; wherefore, I show unto you the way to judge; for every thing which inviteth to do good, and to persuade to believe in Christ, is sent forth by the power and gift of Christ; wherefore ye may know with a perfect knowledge it is of God (Moroni 7:16).
"Amaleki explained that 'there is nothing which is good save it comes from the Lord: and that which is evil cometh from the devil' (Omni 1:25; see also Alma 5:40). This is the great litmus test for determining the truthfulness or rightness of a matter- does it invite and entice one to come unto God, to partake of his goodness and grace, to enjoy the fruits of his Spirit, to gain in time those godly attributes and godly powers which will equip the person to be with and be like God? If it does so, it is of God." (McConkie, Millet, and Top, Doctrinal Commentary on the Book of Mormon, vol. 4, p. 335)