Jehovah's Witnesses, as one example of a group who denies that Jesus is God, claim that Revelation 22:13 is a reference to Jehovah God and not Jesus:
I am the Alpha and the Omega, the first and the last, the beginning and the end.”
It is spoken to John by an angel and not directly by either Jehovah God or Jesus (Rev. 22:8)
Revelation 22:6 says that God sent this angel to John:
And he said to me, “These words are trustworthy and true. And the Lord, the God of the spirits of the prophets, has sent his angel to show his servants what must soon take place.”
The "he" in the above verse is the angel from verse 22:1 and 8:
Then the angel showed me the river of the water of life, bright as crystal, flowing from the throne of God and of the Lamb - v.1
I, John, am the one who heard and saw these things. And when I heard and saw them, I fell down to worship at the feet of the angel who showed them to me - v.8
Later in verse 22:16 Jesus himself confirms to be the one who sent the angel:
“I, Jesus, have sent my angel to testify to you about these things for the churches. I am the root and the descendant of David, the bright morning star.”
What exegetical proof is there that the Alpha and Omega statement of verse 13 is not applied equally to both Jehovah God and Jesus since both sent the same angel in the same instance to proclaim it? Or put another way, how can this be reconciled with the non-trinitarian belief that Jesus is not God?