Bruce R. McConkie
"Christ is ’the true light that lighteth every man that cometh into the world.’ (D. & C. 93:2; John 1:9.) This enlightenment is administered to all men through the Spirit of Christ, or the Spirit of the Lord, or the Light of truth, or the light of Christ -- all of which expressions are synonymous. This Spirit fills the immensity of space, is in all things, and is not to be confused with the Personage of Spirit known as the Holy Ghost (or Spirit of the Lord). (Doctrines of Salvation, vol. 1, pp. 38-54.)
"The light of Christ is the Spirit of the Lord which leads men to accept the gospel and join the Church so that they may receive the gift of the Holy Ghost. Men are commanded to ’live by every word that proceedeth forth from the mouth of God. For the word of the Lord is truth, and whatsoever is truth is light, and whatsoever is light is Spirit, even the Spirit of Jesus Christ. And the Spirit giveth light to every man that cometh into the world; and the Spirit enlighteneth every man through the world, that hearkeneth to the voice of the Spirit.’ (D. & C. 84:44-46.) Those who hearken to this Spirit come into the Church, receiving ’of the Spirit of Christ unto the remission of their sins.’ (D. & C. 20:37; 84:47-48; Alma 19:6; 26:3; 28:14.) Men are born again by following the light of Christ to the point where they receive the actual enjoyment of the gift of the Holy Ghost. (Mosiah 27:24-31; Alma 36.)
“It is because of the light of Christ that all men know good from evil and enjoy the guidance of what is called conscience.” (Mormon Doctrine, pp. 446-7)
Boyd K. Packer
“We are separated from animals by more than upright posture, an articulated thumb, and the size of our brain. We are separated by a conscience…Our conscience might be described as a memory, a residual awareness of who we really are, of our true identity. It is perhaps the best example of the fact that we can become aware of truths because we feel them…This knowledge of right and wrong, is called the light of Christ, moral sense, or conscience, it moderates our actions unless, that is, we subdue it or destroy it…It affirms…the reality of good and evil, justice, mercy, honor, courage, faith, love, and virtue, as well as their necessary opposites, hatred, greed, brutality, and jealousy.” (Latter-day Commentary on the Book of Mormon compiled by K. Douglas Bassett, p. 521)