ISB ~ Revelation 7 v3

sealed:A seal is a mark of ownership and protection (9:4). Here the seal of God is related to the seals of the scroll, giving protection to the believing remnant of Israel, who will pass through the tribulation. This may refer to a grace of spiritual perseverance rather than a guarantee of physical survival. In the broader context of Revelation, there is a contrast between the seal of God stamped on the foreheads of the righteous (7:2) and the mark of the beast inscribed on the brows of the wicked (13:16). The former bears the divine name of God (14:1; 22:4), while the latter bears the demonic name of the beast (13:17) (CCC 1296). See note on 2 Cor 1:22.

• The entire scene parallels Ezek 9:1-7, where a messenger seals the foreheads of the righteous in Israel to protect them from the wrath of God poured out on Jerusalem. The seal was shaped like the Hebrew letter taw, which in ancient script looked like a cross (x or +). Marks of divine protection can be traced as far back as Cain in Gen 4:15.