For similar doxologies see Rom 9:5; Rom 11:36; Rom 16:27; Eph 3:21; 1Ti 1:17.
Forever and ever (εἰς τοὺς αἰῶνας τῶν αἰώνων)
Lit. unto the ages of the ages. See additional note on 2Th 1:9, and comp. Rom 16:27; Phi 4:20; 1Ti 1:17; 2Ti 4:18. Often in Revelation. In lxx. habitually in the singular: see Psa 89:29; 110:3, 30. In the doxology the whole period of duration is conceived as a succession of cycles.