See Who is the Overcomer?
clothed in white garments
See commentary on Revelation 3:4. Clothed is περιβαλεῖται [peribaleitai] , the overcomer will cause himself to be clothed in white.1 The overcomer will be clothed in white garments like those in Laodicea who are counseled to buy ... white garments, that you may be clothed, that the shame of your nakedness may not be revealed (Rev. Rev. 3:18+). This clothing covers nakedness, reminding us of the Hebrew word for atonement, כֻפַּר [ḵuppar] : pual - to be covered over.2 The white garments are a symbol of redemption (Rev. Rev. 4:4+; Rev. 5:8-9+; Rev. 7:9-17+). The sin of the overcomer will be removed from Gods sight by being covered by the righteousness of God (Rom. Rom. 3:5, Rom. 3:21-26; Rom. 10:3; 2Cor. 2Cor. 5:21; Php. Php. 3:9; Jas. Jas. 1:20). Some have also seen the white garments as a possible allusion to the glorified state of the redeemed (Dan. Dan. 12:3; Mtt. Mat. 13:43; Rom. Rom. 8:19, Rom. 8:23; Php. Php. 3:21).
The armies of heaven who appear with the warrior Messiah are arrayed in fine linen, white and pure (Rev. Rev. 19:14+). It would seem, therefore, that the white garments promised to the overcomer in Rev. Rev. 3:5+ represent an attire appropriate to the heavenly state. Since they are made white by washing in the blood of the Lamb (Rev. Rev. 7:13+), the figure is highly appropriate to portray justification.3
I will not
This is emphatic: a double negative (Luke Luke 21:33; John John 6:37; John 8:51; John 13:8; Rev. Rev. 2:11+).
blot out his name from the Book of Life
The church at Sardis had a name and likely had an official roll containing the names of those who attended. Yet it was dead. Jesus directs the church members to be concerned whether they are in the Book of Life rather than the church role. See Book of Life.
confess his name
Christ taught the same in the gospelsthat whoever would confess Him before men, in turn, He would confess before His Father and the angels (Mtt. Mat. 10:32; Luke Luke 12:8). What powerful incentive this is for our witness of Him in the face of skeptics and mockers! When standing before such men, let us consider ourselves to be standing before the very throne of the Father in our confession of the Son. Coming immediately after the promise of not erasing the overcomers name from the book of life, this promise implies that on that future day of reckoning the judge will acknowledge the names written in the book as those who belong to Him.4
1 the one who conquers will cause himself to be clothed in white clothing. Like Gal. Gal. 5:12, this is an example of a causative direct middle. Direct middles are not uncommon with verbs meaning to put on clothes. Daniel B. Wallace, Greek Grammar Beyond the Basics - Exegetical Syntax of the New Testament (Grand Rapids, MI: Zondervan Publishing House and Galaxie Software, 1999, 2002), 424.