Innumerable angels exist in the presence of God in heaven (Revelation 5:11). The Holy Spirit earlier described angels as “ministering spirits sent out to serve for the sake of those who are to inherit salvation” (Hebrews 1:14; see also Psalm 103:20). Angels, then, do not appear on human radars on their own initiative but only when God sends them. Inasmuch as he sends them to serve his people, their appearance here is distinctly a positive for John (and his readers).
1 Then I saw another sign in heaven, great and amazing, seven angels with seven plagues, which are the last, for with them the wrath of God is finished.