This is the fifth beatitude in the Revelation John saw (Revelation 1:3; Revelation 14:13; Revelation 16:15; Revelation 19:9). The term blessed
means be happy, fortunate
(as also in Matthew 5:3–11). This beatitude is not addressed to the martyrs of Revelation 20:4 (though it is about them) but is addressed to John’s readers still living their earthly existence on earth. That is to say, these readers could yet experience pressure to worship the beast and potentially be beheaded themselves (or martyred in some other form). A declaration of being blessed
indicates that future martyrs would also come to life and reign with Christ for the fullness of time God ordains for them (where the thousand years
denotes the remainder of the New Testament era relative to the time they die).
6 Blessed and holy is the one who shares in the first resurrection! Over such the second death has no power, but they will be priests of God and of Christ, and they will reign with him for a thousand years.