The phrase “light of Christ” does not appear in the Bible, although the principles that apply to it are frequently mentioned therein. The precise phrase is found in Alma 28:14, Moro. 7:18, and D&C 88:7. Biblical phrases that are sometimes synonymous to the term “light of Christ” are “spirit of the Lord” and “light of life” (see, for example, John 1:4; 8:12). The “spirit of the Lord,” however, sometimes is used with reference to the Holy Ghost and so must not be taken in every case as having reference to the light of Christ.
The light of Christ is just what the words imply: enlightenment, knowledge, and an uplifting, ennobling, persevering influence that comes upon mankind because of Jesus Christ. For instance, Christ is “the true light that lighteth every man that cometh into the world” (D&C 93:2; see John 1:9). The light of Christ fills the “immensity of space” and is the means by which Christ is able to be “in all things, and is through all things, and is round about all things.” It “giveth life to all things” and is “the law by which all things are governed.” It is also “the light that quickeneth” man’s understanding (see D&C 88:6–13, 41). In this manner, the light of Christ is related to man’s conscience and tells him right from wrong (Moro. 7:12–19).
The light of Christ should not be confused with the personage of the Holy Ghost, for the light of Christ is not a personage at all. Its influence is preliminary to and preparatory to one’s receiving the Holy Ghost. The light of Christ will lead the honest soul who “hearkeneth to the voice” to find the true gospel and the true Church and thereby receive the Holy Ghost (see D&C 84:46–48). Additional references are Alma 19:6; 26:3; D&C 20:27.