And I heard as it were the voice of a great multitude… and as the voice of mighty thunderings, saying, Alleluia: for the Lord God omnipotent reigneth.
I suppose the first thing to do would be to define omnipotence. It comes, of course, from omni, meaning “all,” and potent, meaning “able to do and to have power.” And so omnipotent means “able to do all and to have all power.” It means having all the potency there is.
Then we come to a second word, Almighty…. Now that means exactly the same thing as omnipotent…. Almighty means “having an infinite and absolute plenitude of power.” When you use the words infinite and absolute you can only be talking about one person—God.
There is only one infinite Being, because infinite means without limit. And it is impossible that there should be two beings in the universe without limit. So if there is only one, you are referring to God. Even philosophy and human reason, as little as I think of them, have to admit this….
God has power and whatever God has is without limit; therefore, God is omnipotent. God is absolute and whatever touches God or whatever God touches is absolute; therefore, God’s power is infinite; God is Almighty. AOGII072, 074
What assurance to know I rest in the arms of an all-powerful God. Alleluia, for the Lord God omnipotent reigns! Amen. 
19:6 Now another song breaks out in heaven, as “loud as many water’s noise, loud as thunders to the ear.” A great “Alleluia” swells in celebration of the reign of the Lord God Omnipotent!
6. And I heard as it were the voice of a great multitude and as it were the sound of many waters and as it were the sound of mighty peals of thunder, saying, “Hallelujah, because our Lord God Almighty rules.”
John listened to a hymn that sounded as if it were sung by a vast multitude. He does not identify this throng, but because the wording is the same as in verse 1, it appears that the multitude has the same identity. They sing both the opening and the concluding hymns in this chapter; in both they sing the same notes of praise and adulation. Here are inconspicuous echoes of the hymns the multitudes sang in both chapters 5 and 7.
The voice that John hears he compares with sounds taken from nature: the sounds of many waters and of mighty peals of thunder. John describes the voice of Jesus’ appearance on the isle of Patmos as a rushing sound coming from many waters (1:15; see 14:2; Ezek. 1:24; 43:2). And the phrase mighty peals of thunder conveys the idea of loudness that can be heard everywhere (Rev. 6:1; 14:2). These two phrases indeed point to God’s power, majesty, and glory. And the mighty voice of the countless multitude attests to expressions of joy and thankfulness for the privilege of being the bride of Christ.
This voice, conveying the sound of a multitude of people talking at the same time, rises from the pleasing tones of bubbling water and then swells to the crashing crescendo of thunderclaps. These sounds are like people who begin singing softly but then culminate their hymn in resounding overtones. The first word of the song is Hallelujah, which has now occurred four times in these hymns. It is followed by a clause that gives the reason for this note of jubilation, “because our Lord God Almighty rules.” The verb in this clause can be interpreted to read that the Lord “has begun to rule.” The Lord God, as the descriptive label Almighty indicates, has always been the ruler over his great creation. But now the kingdom of the Antichrist has come to its anticipated end, and the Lord God is the supreme ruler in the vast universe he has created. In Revelation, the term the Lord God Almighty appears seven times and characterizes God’s sovereignty. While on earth Domitian was honored as dominus et deus (Lord and God), the heavenly chorus sings in triumph that God occupies the true seat of power in the world (see Ps. 93:1; 97:1; 99:1; 1 Chron. 16:31; Zech. 14:9). Last, the possessive personal pronoun our in “our Lord God Almighty rules” makes the chorus inclusive: the saints in heaven and on earth are one.
6 Finally the cycle of praise is completed with the reverberating sounds of another great multitude. If the multitude in v. 1 was angelic, then this one would most certainly be the great redeemed throngs (cf. 7:9). They utter the final Hallel in words reminiscent of the great kingship psalms (93:1; 97:1; 99:1). The first of these psalms is used in the synagogue in Sabbath morning and evening services and also in the Armenian church liturgy for Easter Sunday (Werner, Sacred Bridge, 153). It is also the prelude to the messianic Psalms 95–99 and has as its theme the eternal sovereignty of God, who will conquer all his enemies (cf. Hertz, Daily Prayer Book, 362). The Greek verb ebasileusen (“reigns”), an ingressive aorist, may better be rendered, “has begun to reign.”
 Tozer, A. W., & Eggert, R. (2015). Tozer on the almighty god: a 365-day devotional. Chicago, IL: Moody Publishers.
 MacDonald, W. (1995). Believer’s Bible Commentary: Old and New Testaments. (A. Farstad, Ed.) (p. 2376). Nashville: Thomas Nelson.
 Kistemaker, S. J., & Hendriksen, W. (1953–2001). Exposition of the Book of Revelation (Vol. 20, pp. 512–513). Grand Rapids: Baker Book House.
 Johnson, A. F. (2006). Revelation. In T. Longman III & D. E. Garland (Eds.), The Expositor’s Bible Commentary: Hebrews–Revelation (Revised Edition) (Vol. 13, p. 755). Grand Rapids, MI: Zondervan.