The night has advanced, and the day, etc. This is the season which he had just mentioned; for as the faithful are not as yet received into full light, he very fitly compares to the dawn the knowledge of future life, which shines on us through the gospel: for day is not put here, as in other places, for the light of faith, (otherwise he could not have said that it was only approaching, but that it was present, for it now shines as it were in the middle of its progress,) but for that glorious brightness of the celestial life, the beginnings of which are now seen through the gospel. The sum of what he says is, -- that as soon as God begins to call us, we ought to do the same, as when we conclude from the first dawn of the day that the full sun is at hand; we ought to look forward to the coming of Christ. He says that the night had advanced, because we are not so overwhelmed with thick darkness as the unbelieving are, to whom no spark of life appears; but the hope of resurrection is placed by the gospel before our eyes; yea, the light of faith, by which we discover that the full brightness of celestial glory is nigh at hand, ought to stimulate us, so that we may not grow torpid on the earth. But afterwards, when he bids us to walk in the light, as it were during the day time, he does not continue the same metaphor; for he compares to the day our present state, while Christ shines on us. His purpose was in various ways to exhort us, -- at one time to meditate on our future life; at another, to contemplate the present favor of God.

The night - The word "night," in the New Testament, is used to denote "night" literally (Matthew 2:14, etc.); the starry heavens Revelation 8:12; and then it denotes a state of "ignorance" and "crime," and is synonymous with the word "darkness," as such deeds are committed commonly in the night; 1-Thessalonians 5:5. In this place it seems to denote our present imperfect and obscure condition in this world as contrasted with the pure light of heaven The "night," the time of comparative obscurity and sin in which we live even under the gospel, is far gone in relation to us, and the pure splendors of heaven are at hand,
Is far spent - Literally, "is cut off." It is becoming "short;" it is hastening to a close.
The day - The full splendors and glory of redemption in heaven. Heaven is often thus represented as a place of pure and splendid day; Revelation 21:23, Revelation 21:25; Revelation 22:5. The times of the "gospel" are represented as times of "light" (Isaiah 60:1-2; Isaiah 60:19-20, etc.); but the reference here seems to be rather to the still brighter glory and splendor of heaven, as the place of pure, unclouded, and eternal day.
Is at hand - Is near; or is drawing near. This is true respecting all Christians. The day is near, or the time when they shall be admitted to heaven is not remote. This is the uniform representation of the New Testament; Hebrews 10:25; 1-Peter 4:7; James 5:8; Revelation 22:10; 1-Thessalonians 5:2-6; Philippians 4:5. That the apostle did not mean, however, that the end of the world was near, or that the day of judgment would come soon, is clear from his own explanations; see 1-Thessalonians 5:2-6; compare 2 Thes. 2.
Let us therefore - As we are about to enter on the glories of that eternal day, we should be pure and holy. The "expectation" of it will teach us to "seek" purity; and a pure life alone will fit us to enter there; Hebrews 12:14.
Cast off - Lay aside, or put away.
The works of darkness - Dark, wicked deeds, such as are specified in the next verse. They are called "works of darkness," because darkness in the Scriptures is an emblem of crime, as well as of ignorance, and because such deeds are commonly committed in the night; 1-Thessalonians 5:7, "They that be drunken, are drunken in the night;" compare John 3:20; Ephesians 5:11-13.
Let us put on - Let us clothe ourselves with.
The armour of light - The word "armor" ὅπλα hopla properly means "arms," or instruments of war, including the helmet, sword, shield, etc. Ephesians 6:11-17. It is used in the New Testament to denote the "aids" which the Christian has, or the "means of defense" in his warfare, where he is represented as a soldier contending with his foes, and includes truth, righteousness, faith, hope, etc. as the instruments by which he is to gain his victories. In 2-Corinthians 6:7, it is called "the armor of righteousness on the right hand and on the left." It is called armor of light, because it is not to accomplish any deeds of darkness or of crime; it is appropriate to one who is pure, and who is seeking a pure and noble object. Christians are represented as the "children of light;" 1-Thessalonians 5:5; Note, Luke 16:8. By the armor of light, therefore, the apostle means those graces which stand opposed to the deeds of darkness Romans 13:13; those graces of faith, hope, humility, etc. which shall be appropriate to those who are the children of the day, and which shall be their defense in their struggles with their spiritual foes. see the description in full in Ephesians 4:11-17.

The night is far spent - If we understand this in reference to the heathen state of the Romans, it may be paraphrased thus: The night is far spent - heathenish darkness is nearly at an end. The day is at hand - the full manifestation of the Sun of righteousness, in the illumination of the whole Gentile world approaches rapidly. The manifestation of the Messiah is regularly termed by the ancient Jews יום yom, day, because previously to this all is night, Bereshith rabba sect. 91, fol. 89. Cast off the works of darkness - prepare to meet this rising light, and welcome its approach, by throwing aside superstition, impiety, and vice of every kind: and put on the armor of light - fully receive the heavenly teaching, by which your spirits will be as completely armed against the attacks of evil as your bodies could be by the best weapons and impenetrable armor. This sense seems most suitable to the following verses, where the vices of the Gentiles are particularly specified; and they are exhorted to abandon them, and to receive the Gospel of Christ. The common method of explanation is this: The night is far spent - our present imperfect life, full of afflictions, temptations, and trials, is almost run out; the day of eternal blessedness is at hand - is about to dawn on us in our glorious resurrection unto eternal life. 'Therefore, let us cast off - let us live as candidates for this eternal glory. But this sense cannot at all comport with what is said below, as the Gentiles are most evidently intended.

The night is far spent, the day is (i) at hand: let us therefore cast off the works (k) of darkness, and let us put on the armour of light.
(i) In other places we are said to be in the light, but yet so that it does not yet appear what we are, for as yet we see but as it were in the twilight.
(k) That kind of life which those lead that flee the light.

The night is far spent,.... Not of Jewish darkness, which was gone, and was succeeded by the Gospel day; nor of former ignorance in Gentilism and unregeneracy, for that was past, and the true light shined; much less of security in the latter day, which was not yet come on; rather of persecution and distress for Christ's sake; but it is best of all to understand it of the present time of life; so it is called by the Jews (g), , "this world is like to the night": and which, in the best of saints, is attended with imperfection and darkness, errors and mistakes, in principle and practice, in doctrine and conversation; however, it is far spent, and in a little time will be over:
the day is at hand; not the Gospel day, for that was already come; nor the day of grace, and spiritual light and comfort to their souls, for that also had taken place; nor the latter day glory, which then was at a distance; rather the approaching day of deliverance from present persecutions; but it is much better to understand it of the everlasting day of glory, which to particular persons was then, and now is at hand; a little while, and the night of darkness, affliction, and disconsolation will be over, and the day of glory will succeed, when there will be no more night, no more darkness, no more doubts, fears, and unbelief; but one continued series of light, joy, and comfort, and an uninterrupted communion with Father, Son, and Spirit; and which is another reason why the saints should not indulge themselves in sleep, but be active, since the halcyon days are at hand, as well as a reason why they should attend to the following exhortations:
let us therefore cast off the works of darkness; as the apostle had made use of the metaphors of night and day, and of sleep, and awaking out of sleep, and rising in the morning to business, so he continues the same; and here alludes to persons throwing off their bed clothes, and covering of the night, and putting on proper raiment for the day. By "works of darkness" are meant evil works, which are opposite to the light; to God, who is light itself; to Christ, the light of the world; to the word of God, both law and Gospel, which is a light to our paths; to both the light of nature, and the light of grace: and which spring from the darkness of the mind, and are encouraged to by the god of this world, and by his angels, the rulers of the darkness of it; and which are generally done in the dark, and are such as will not bear the light; and, if grace prevent not, will end in outer darkness, in blackness of darkness, reserved by the justice of God, as the punishment of them. "Casting them off" expresses a dislike of them, a displicency with them, and an abstinence from them. Some copies read, "the armour of darkness", which agrees with what follows:
and let us put on the armour of light; the whole armour of God, the use of which lies in the exercise of grace, and discharge of duty; particularly good works are designed here, which though they are not the believer's clothing, his robe of justifying righteousness, they are both his ornament and his armour; by which he adorns the doctrine of Christ, and defends his own character and principles against the charges find calumnies of then: these being performed aright, spring from the light of grace in a regenerate man, and are such as will bear the light to be seen of men; and are the lights which are to shine before men, that they beholding them, may glorify God; so virtue was by Antisthenes (h), called , "armour which cannot be taken away": the allusion is thought to be to the bright and glittering armour of the Romans; the Alexandrian copy reads, "the words of light".
(g) Tzeror Hammor, fol. 24. 4. (h) Diogen. Laert. l. 6. in Vita Antisthen. & Hesychius de viris illustr. p. 17.

The night--of evil
is far spent, the day--of consummated triumph over it
is at hand: let us therefore cast off--as a dress
the works of darkness--all works holding of the kingdom and period of darkness, with which, as followers of the risen Saviour, our connection has been dissolved.
and let us put on the armour of light--described at length in Ephesians 6:11-18.