No article. Hence Rev., an eternal Gospel. Milligan thinks this is to be understood in the same sense as prophesying (Rev 10:11). Αἰώνιον includes more than mere duration in time. It is applied to that of which time is not a measure. As applied to the Gospel it marks its likeness to Him whose being is not bounded by time.
To preach unto (εὐαγγελίσαι ἐπὶ)
Rev., proclaim, which is better, because more general and wider in meaning. Ἑπί which is omitted from the Rec. Tex. is over, throughout the extent of. Compare Mat 24:14.
That dwell (κατοικοῦντας)
Read καθημένους that sit. So Rev., in margin. Compare Mat 4:16; Luk 1:79.