Adam Clarke on Romans 13:12

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.