He that overcometh - See the notes on Revelation 2:7.
The same shall be clothed in white raiment - Whosoever he may be that shall overcome sin and the temptations of this world, shall be admitted to this glorious reward. The promise is made not only to those in Sardis who should be victorious, but to all in every age and every land. The hope that is thus held out before us, is that of appearing with the Redeemer in his kingdom, clad in robes expressive of holiness and joy.
And I will not blot out his name out of the book of life - The book which contains the names of those who are to live with him forever. The names of his people are thus represented as enrolled in a book which he keeps - a register of those who are to live forever. The phrase “book of life” frequently occurs in the Bible, representing this idea. See the notes on Philippians 4:3. Compare Revelation 15:3; Revelation 20:12, Revelation 20:15; Revelation 21:27; Revelation 22:19. The expression “I will not blot out” means, that the names would be found there on the great day of final account, and would be found there forever. It may be remarked, that as no one can have access to that book but he who keeps it, there is the most positive assurance that it will never be done, and the salvation of the redeemed will be, therefore, secure. And let it be remembered that the period is coming when it will be felt to be a higher honor to have the name enrolled in that book than in the books of heraldry - in the most splendid catalogue of princes, poets, warriors, nobles, or statesmen that the world has produced.
But I will confess his name, ... - I will acknowledge him to be my follower. See the notes on Matthew 10:32.