“The one who conquers, I will make him a pillar in the temple of my God. Never shall he go out of it, and I will write on him the name of my God, and the name of the city of my God, the new Jerusalem, which comes down from my God out of heaven, and my own new name” (Rev. 3:12 ESV).
The book of Revelation is filled with terminology and images borrowed from the OT. Isaiah had prophesied that the people of God would be called by “a new name” (Isa. 62:2; 65:15). In the NT the name exalted above all others is that of Jesus Christ (Phil. 2:9-11), through whom salvation is granted (Acts 4:12) and the identifying moniker of the new-covenant people of God (Acts 11:26; Jas. 2:7).
In Revelation 3:12, a message to the first-century church in the Asian city of Philadelphia, Christians are being encouraged to persevere and to overcome the challenges they are facing in order to be established in God’s “temple” (= the church, 1 Cor. 3:16-17; Eph. 2:21-22; 1 Tim. 3:15), wearing God’s name (1 Cor. 10:32; 11:22; 15:9; 2 Tim. 2:19; Rev. 14:1) and the name of God’s city (= the church, Heb. 12:22-23; Rev. 21:2-3; 22:14) and “my new name” (Jesus Christ) – a threefold emphasis identifying and confirming to whom the Lord’s faithful ones belong.
--Kevin L. Moore
Image credit: https://www.phillipsphillipslaw.com/blog/2014/11/20/fathers-rights-changing-or-hyphenating-your-childs-last-name