Well, one thing that's helpful to remember in Revelation, is that numbers mean things, sometimes in a different way than they do in historical narratives because Revelation is an “apocalyptic work” that shows this thing by pictures. It seems to represent all of God's people, from the Old Testament and the New Testament.
The 12 Tribes of Israel… times the 12 apostles and those that they represent… times a very great number: 1,000. And so 12 x 12 x 1,000 is 144,000. And these are marked with the Seal of God on their foreheads. This shows us that they bow to the Lamb and to His Father, and we can contrast this with the Mark of the Beast that appears on those who do not belong to the Lamb.
And so instead of being sealed, they merely have the Mark of the Beast, which indicates being owned not by the Lamb, but by the Beast. And that they follow his ways. And so there's a contrast between the 144,000 in
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