But ye, brethren. He now admonishes them as to what is the duty of believers, that they look forward in hope to that day, though it be remote. And this is what is intended in the metaphor of day and light. The coming of Christ will take by surprise those that are carelessly giving way to indulgence, because, being enveloped in darkness, they see nothing, for no darkness is more dense than ignorance of God. We, on the other hand, on whom Christ has shone by the faith of his gospel, differ much from them, for that saying of Isaiah is truly accomplished in us, that while darkness covers the earth, the Lord arises upon us, and his glory is seen in us. (Isaiah 60:2) He admonishes us, therefore, that it were an unseemly thing that we should be caught by Christ asleep, as it were, or seeing nothing, while the full blaze of light is shining forth upon us. He calls them children of light, in accordance with the Hebrew idiom, as meaning -- furnished with light; as also children of the day, meaning -- those who enjoy the light of day. [1] And this he again confirms, when he says that we are not of the night nor of darkness, because the Lord has rescued us from it. For it is as though he had said, that we have not been enlightened by the Lord with a view to our walking in darkness.

Footnotes

1 - "It is day' with them. It is not only day' round about them, (so it is wherever the gospel is afforded to men,) but God hath made it day' within." --Howe's Works, (Lond. 1822,) vol. 6, p. 294. -- Ed.

But ye, brethren, are not in darkness, that that day should overtake you as a thief - The allusion here is to the manner in which a thief or robber accomplishes his purpose. He comes in the night, when people are asleep. So, says the apostle, the Lord will come to the wicked. They are like those who are asleep when the thief comes upon them. But it is not so with Christians. They are, in relation to the coming of the day of the Lord, as people are who are awake when the robber comes. They could see his approach, and could prepare for it, so that it would not take them by surprise.

But ye, brethren, are not in darkness - Probably St. Paul refers to a notion that was very prevalent among the Jews, viz.: that God would judge the Gentiles in the night time, when utterly secure and careless; but he would judge the Jews in the day time, when employed in reading and performing the words of the law. The words in Midrash Tehillim, on Psalm 9:8, are the following: When the holy blessed God shall judge the Gentiles, it shall be in the night season, in which they shall be asleep in their transgressions; but when he shall judge the Israelites, it shall be in the day time, when they are occupied in the study of the law. This maxim the apostle appears to have in view in the 4th, 5th, 6th, 7th, and 8th verses. (1-Thessalonians 5:4-8)

(2) But ye, brethren, are not in darkness, that that day should overtake you as a thief.
(2) Returning to exhortations, he warns us who are enlightened with the knowledge of God, that it is our duty not to live securely in pleasures, lest we be suddenly taken in a dead sleep in pleasures. But contrary to this we are to have an eye to the Lord, and not allow ourselves to be oppressed with the cares of this world, for pleasures are fitting for the darkness of the night, and having an eye to the Lord is fitting for the light.

But ye, brethren, are not in darkness,.... In a state of unregeneracy, which is a state of darkness, blindness, and ignorance, and which is the condition of all men by nature; they are born in darkness, and are brought up in it, and willingly, walk in it; they are covered with it, as the earth was covered with darkness in its first creation; and dwell in it, as the Egyptians did for some days, in thick darkness, darkness which might be felt; their understandings are darkened with respect to the true knowledge of God, the nature of sin, the way of salvation by Christ, the work of the spirit of God upon the soul, and the necessity of it, the Scriptures of truth, and the mysteries of the Gospel; and which is the case of God's elect themselves, while unregenerate: but now these persons were called out of darkness, turned from it, and delivered from the power of it; and therefore knew that the day of the Lord comes as above described, by the metaphors of a thief in the night, and a woman with child, and needed not to be informed about that matter: or
that that day should overtake you as a thief; or seize and lay hold upon you as a thief who comes in the dark, and lays hold upon a person suddenly; but these saints were not in the dark, but in the light, and so could see when the day of the Lord came; and would not be surprised with it, as a man is seized with terror and fright, when laid hold on by a thief; since they would be, or at least should be on their watch, and be looking out for, and hasting to the coming of the day of God.

not in darkness--not in darkness of understanding (that is, spiritual ignorance) or of the moral nature (that is, a state of sin), Ephesians 4:18.
that--Greek, "in order that"; with God results are all purposed.
that day--Greek, "THE day"; the day of the Lord (Hebrews 10:25, "the day"), in contrast to "darkness."
overtake--unexpectedly (compare John 12:35).
as a thief--The two oldest manuscripts read, "as (the daylight overtakes) thieves" (Job 24:17). Old manuscripts and Vulgate read as English Version.

Ye, brethren, are not in darkness. The Christian has been fully instructed, is a child of the light, and knows that he must always be ready. He follows the Light of the World.
Ye are all the children of light. They are of the light, of the day, because they have come to Christ for light, and are taught of him. Hence on this subject they are fully informed. Those are of the night, who turn away from the light and refuse to accept it.
Therefore let us not sleep. Since Christians are of the day, they should be wide awake. Day is not the time for sleep. A sleep of the spiritual faculties, which renders one insensible to danger, is meant. Instead of sleeping, Christians should watch and be sober. For a comment declaring how we should obey this, turn to Luke 21:34, Luke 21:36 : "Take heed to yourselves, etc."
They that sleep, sleep in the night. Hence, Christians who are of the day, should be wakeful and watching.
They that be drunken, are drunken in the night. In most countries they are ashamed to be seen intoxicated, and hence choose the night. In the East it is so. Peter thought the fact that it was day, and only nine o'clock, was proof that the scenes of Pentecost were not due to wine (Acts 2:15).

Ye are not in darkness - Sleeping secure in sin.