This angel must “tell good news” (that is the literal meaning of the Greek word translated “proclaim”) “to those who dwell on earth.” This includes believers (the “saints” of Revelation 14:12) and unbelievers alike. Concerning the latter, Revelation 13:3 had told us that the whole earth marveled as they followed the beast
(see also Revelation 13:12). Each of these dragon-worshippers, irrespective of nationality or tribal allegiance or language preference or colour of skin, is made to hear this eternal gospel.
What they hear from the angel clearly clashes with their practice of worshipping the dragon and his lackeys and so is to their ears not good news. Of course, their evaluation does not take away from the fact that God’s message is eternal gospel.
6 Then I saw another angel flying directly overhead, with an eternal gospel to proclaim to those who dwell on earth, to every nation and tribe and language and people.