1 Thessalonians 5

Speaking to the saints at Thessalonia, Paul writes -

"Ye are all the children of light, and the children of the day..." (New Testament 1 Thessalonians 5:5)

As children of light or of the day, Paul warns -

"Therefore let us not sleep, as do others; but let us watch and be sober.
7 For they that sleep sleep in the night; and they that be drunken are drunken in the night." (New Testament 1 Thessalonians 5:6 - 7)

To remain children of light he admonishes -

"...let us, who are of the day, be sober, putting on the breastplate of faith and love; and for an helmet, the hope of salvation." (New Testament 1 Thessalonians 5:8)

We begin to understand more what "children of light" means as James teaches -

"Every good gift and every perfect gift is from above, and cometh down from the Father of lights..." (New Testament James 1:17)

The light is truth or the light of the gospel of Jesus Christ or as revealed by the Lord in modern day -

"...I have sent mine everlasting covenant into the world, to be a light to the world, and to be a standard for my people, and for the Gentiles to seek to it, and to be a messenger before my face to prepare the way before me." (Doctrine and Covenants Section 45:9)

Alma described what happened to their parents as they chose to accept His everlasting covenant. He said the Lord -

"...changed their hearts; yea, he awakened them out of a deep sleep, and they awoke unto God. Behold, they were in the midst of darkness; nevertheless, their souls were illuminated by the light of the everlasting word..." (Book of Mormon Alma 5:7)

And thus they became children of light for as they did look -

"...forward with one eye, having one faith and one baptism, having their hearts knit together in unity and in love one towards another...they became the children of God." (Book of Mormon Mosiah 18:21 - 22)

This is why the Lord has-

"...commanded you to bring up your children in light and truth." (Doctrine and Covenants Section 93:40)

That all our children may also be "children of light".