Saying, we give thee thanks, O Lord God
The person addressed is the Lord Jesus Christ, whose the kingdoms are become, and who now reigns in great power and authority; he is Lord of all, and truly and properly God, and the Almighty, as his works of creation, preservation, redemption, raising himself from the dead declare; and each of these titles exceedingly well suit him, when his visible kingdom on earth will be so greatly enlarged:
which art, and wast, and art to come:
the everlasting, "I am", the unchangeable Jehovah: the phrase is expressive of the eternity and immutability, (See Gill on Revelation 1:8); and it may be observed, whereas in this description of him it is said, "and art to come", this therefore does not belong to his personal, but to his spiritual reign; he will not be as yet come in person, to raise the dead, and judge the world, when these voices shall be in heaven, and these congratulations of the elders be made: the reason of their praise and thanksgiving follows,
because thou hast taken to thee thy great power, and hast
power always belonged to him, as God; he always was the mighty God, and, as such, help for his people was laid upon him, he being mighty to save, and able to bear the government of them, laid on his shoulders; and, as Mediator, all power in heaven, and in earth, was given to him at his resurrection; and he had a name given him above every name, when exalted at the right hand of God, and was made, or declared, Lord and Christ; and from that time he has, in some measure, exerted his power and reigned: he endued his apostles with power from on high; and he went forth in the ministry of the Gospel conquering, and to conquer; and has ever since reigned in the hearts of his people; but now he will manifest and display his "great" power; he will show it more openly, and use it more extensively; his kingdom shall be from sea to sea, and from the river to the ends of the earth; he shall be King over all the earth; his power has been seen in ages past, but now the "greatness" of his power will be made manifest; he has always had a kingdom on earth, but now the, "greatness" of the kingdom, under the whole heaven, will be his.