Paul's thought moved from identifying responsibilities to urging their practice. What lies before us as Christians provides essential motivation for doing so.
13:11 "This"refers to the duties urged earlier, not only in this chapter but in chapter 12 also. It is important that we follow God's will carefully because the final phase of our salvation will take place very soon (i.e., glorification, cf. 1 Pet. 1:9). We must be ready to meet the Lord and to give an account of our stewardship to Him (cf. Phil. 3:20; 1 Thess. 5:6; 1 Cor. 15:34). It is possible for us to go through our lives as believers lethargic and insensible, but such a condition is not wise in view of what lies ahead of us.
13:12 Here Paul was thinking similarly to the way he thought when he wrote 1 Thessalonians 5:1-11. The night represents our earthly life plagued as it is with spiritual darkness and danger. When the Lord Jesus calls us to Himself at the Rapture, a new day will begin for us in which we will walk and live in sinless light. In view of this prospect we need to prepare for it by laying aside evil deeds as a garment and putting on deeds of holiness. Paul called these new clothes armor because we are still at war with sin and the forces of evil (cf. Eph. 6:11).
"Christ's return is the next event in God's plan; Paul knew it could take place at any time and sought to prepare Christians--both in his generation and in ours--for that blessed hope.'"380
13:13 Our behavior, and specially those things Paul called on his readers to do in 13:1-10, should be distinctively Christian since we live among unbelievers. The practices he urged us to avoid here were common in Corinth where Paul wrote this epistle. He observed them constantly. Intemperance often leads to sexual sin that frequently results in contention and quarreling.
13:14 In one sense every believer puts on Jesus Christ when he or she trusts Him as Savior (Gal. 3:27). However in another sense we put Him on when we dedicate ourselves to Him as our lord (12:1). The first step in putting on the armor of light (v. 12) is committing ourselves to follow Jesus Christ wholeheartedly.
Still dedicating is not all that is necessary. There must also be a deliberate turning away from desires to indulge the flesh (cf. ch. 6; 2 Tim. 2:22; 1 Pet. 2:11).
Chapter 13 deals with living in the world as a Christian. Paul counselled submission to human government and love for all people while we actively wait for our Lord to appear.