Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them. (Revelation 7:15)
Gr. naos, a word emphasizing the temple as the dwelling place of God (see on ch. 3:12).
Shall dwell.
Gr. skēnoō (see on John 1:14). The clause may be translated, “He will pitch his tent [or, “tabernacle”] over them.” Casting his words into the future tense, the elder looks forward to the endless ages of eternity, throughout which the saved may be confident that God will indeed dwell in their midst. Never shall they be deprived of His presence, His sustenance, and His favor. To be without the presence of God is utter loss; to have Him dwell among us is salvation evermore.
Therefore.
The righteous, victorious state of this blessed company makes it possible for those who comprise the group to stand continually in the presence of God. If their robes were not white, they could not abide His presence.