Revelation 13:6

he opened his mouth in blasphemy against God, to blaspheme His name, His tabernacle, and those who dwell in heaven.
The TR text designates as many as four targets for the blasphemy of the beast: (1) God; (2) His name; (3) His tabernacle; and 4) those who dwell in heaven. The last three could also be taken as an elaboration of the first, blasphemy against God consisting of... Unlike the TR text, in the MT and NU texts the phrase, those who dwell in heaven, is not separated from the rest of the sentence by καὶ [kai] (“and”). Thus, those who dwell in heaven is taken in apposition to His tabernacle. “And he opened his mouth in blasphemies against God, to blaspheme His name and His tabernacle, that is, those who dwell in heaven.”

those who dwell in heaven.
Τοὺς ἐν τῷ οὐρανῷ σκηνοῦντας [Tous en tō ouranō skēnountas] , present tense participle: those presently dwelling in heaven. These are the ones who rejoiced over the casting out of Satan from heaven and the overcoming of Satan by the saints (Rev. Rev. 12:11-12+). This includes an innumerable company of angels (Heb. Heb. 12:22; Rev. Rev. 5:11+), the church having been taken in the Rapture (Rev. Rev. 5:9+), “The catching away of so many people of God must needs leave a deep impression behind it. The slain and abused bodies of the Two Witnesses are visibly revived, and taken up into the sky before the eyes of Antichrist’s minions. This was a grand and most convincing evidence against him and all his infamous pretensions, a manifest token of his devilish falsity and approaching doom. And he needs above all to break it down, to cast discredit and dishonour upon it, and to root out the very idea if he can. Hence his particular railing and impatience with reference to this divine tent of the glorified ones, and his virulent blaspheming of those who tabernacle in it. . . How blessed are they who through faith and watchfulness have been accounted worthy to escape his power by being caught up to God ere he is revealed!”¹ the martyrs under the fifth seal (Rev. Rev. 6:9-11+), those out of the Great Tribulation (Rev. Rev. 7:9+), the two witnesses (Rev. Rev. 11:12+), and others who have died prior to this point (Rev. Rev. 12:11+; Rev. 20:4+), many of which resisted the Beast to attain “victory” (Rev. Rev. 15:2+). The steadfast faith of believers to the point of death enrages the Beast for the threat of persecution and death is the only device available to him to coerce their worship—a worship which is motivated by the burning jealousy of the dragon who empowers him. The horrible experience of those who come out of the Great Tribulation is ultimately tempered by their intimate dwelling with God (Rev. Rev. 7:15-17+). See The Abiding Presence of God.

Notes

¹ J. A. Seiss, The Apocalypse: Lectures on the Book of Revelation (Grand Rapids, MI: Zondervan Publishing House, 1966), 328.