We are looking at the various references, in the book of Revelation, to the Triune God. Some references are to all three persons, while other references are to one or more of the persons of the Godhead.
Revelation 7:9-11, 17
After this I looked, and behold, a great multitude that no one could number, from every nation, from all tribes and peoples and languages, standing before the throne and before the Lamb, clothed in white robes, with palm branches in their hands, 10 and crying out with a loud voice, “Salvation belongs to our God who sits on the throne, and to the Lamb!”
For the Lamb in the midst of the throne will be their shepherd,
and he will guide them to springs of living water,
and God will wipe away every tear from their eyes.
The Holy Bible: English Standard Version. (2016). (Re 7:9–10, 17). Wheaton, IL: Crossway Bibles.
Notice that salvation belongs to two persons: to our God who sits on the throne, and to the Lamb. Salvation does not belong to one person: to our God who sits on throne who is the Lamb. There is a distinction of persons. The same distinction appears in verse 17 where the Lamb guides and God (the Father) wipes away tears. Verse 15 supports the distinction of persons in these verses.
The collective witness of the book of Revelation is that the Lamb is God, in particular Jesus the Son of God. The collective witness of the book of Revelation is that the Lamb of God is not the same person as God who sits on the throne. The collective witness of the book of Revelation is that the Lamb of God sits on the throne with God and receives worship as God. Either the angels are guilty of worshiping that which is not God (namely the Lamb). Or, the angels are faithful in their monotheism by worshiping the Lamb and God; two distinct persons who exists in perfect unity as God.