After the apostle Paul encourages the church at Rome to love their neighbors and thereby fulfill the second table of the Law, he draws a glorious picture of the life of Christian by depicting it as a single day on this earth.
He begins by writing, “Besides this you know the time, that the hour has come for you to wake from sleep. For salvation is nearer to us now than when we first believed” (v. 13:11). The picture that the apostle is giving is that of person who is lying in bed at dawn, and the light of the day is breaking over the horizon. The person, prior to the dawn, was ever asleep and his life was characterized by the darkness of night. But now, he has seen his salvation and has believed, and for him, “the night is far gone; the day is at hand” (v. 13:12a).
For those to whom the apostle is speaking, the darkness of their former existence is far gone, and the light of day is now their only existence. For this reason, the apostle exhorts them to throw off the works of darkness that formerly characterized their lives, and encourages them instead to put on the armor of light. And when the Christian wakes to God in this life, he wakes into enemy territory, and he therefore must do two things: one, cast off works of darkness, and, two, put on the armor of light.