This is an excerpt from In Wisdom and Order, by Boyd K. Packer.
The Spirit of Christ can enlighten the inventor, the scientist, the painter, the sculptor, the composer, the performer, the architect, the author to produce great, even inspired things for the blessing and good of all mankind.
This Spirit can prompt the farmer in his field and the fisherman on his boat. It can inspire the teacher in the classroom, the missionary in presenting his discussion. It can inspire the student who listens. And of enormous importance, it can inspire husband and wife, and father and mother.
This inner Light can warn and guard and guide. But it can be repulsed by anything that is ugly or unworthy or wicked or immoral or selfish.
The Light of Christ existed in you before you were born (see D&C 93:23, 29–30), and it will be with you every moment that you live and will not perish when the mortal part of you has turned to dust. It is ever there.
Every man, woman, and child of every nation, creed, or color—everyone, no matter where they live or what they believe or what they do—has within them the imperishable Light of Christ. In this respect, all men are created equally. The Light of Christ in everyone is a testimony that God is no respecter of persons (see D&C 1:35). He treats everyone equally in that endowment with the Light of Christ.
It is important for a teacher or a missionary or a parent to know that the Holy Ghost can work through the Light of Christ. A teacher of gospel truths is not planting something foreign or even new into an adult or a child. Rather, the missionary or teacher is making contact with the Spirit of Christ already there. The gospel will have a familiar “ring” to them. Then the teaching will come “to the convincing of [those who will listen] that Jesus is the Christ, the Eternal God, manifesting himself unto all nations” (Book of Mormon, title page). (Body K. Packer, In Wisdom and Order [Salt Lake City: Deseret Book, 2013], 154–55).