It is the voice of Christ; we have already been told, and that is confirmed as the passage continues. Alpha and Omega are the first and last letters of the Greek alphabet.
This is how the Book of Revelation starts because the book is going to be about the great battle between the world and the church, and we shall at times be downtrodden and persecuted. We shall find ourselves very much in the minority, we shall be crushed by hostile powers, and the world will at times seem all powerful. But the Book of Revelation begins on this note: ‘I am the Alpha and the Omega, the Almighty.’ All the great ones in the world cannot even begin to compare with the power of Christ and his sovereignty, and his authority. We are his, and we are in his hand, and we are under his rule, and under his protection. There is nothing therefore that we cannot ask him. We may bring him all those troubles which are too great for us to burden any other human being with. We can place in his hands all the complexities of our own emotions, hopes and fears, things which are part of us and things beyond our understanding.
How can such a one ever be thwarted? He planned everything even before his enemies made their first move against him, before they planned their first strategy, or even before they existed. After Satan has assaulted Christ with the full force of his subtle temptations, and after the wicked have committed every sin that they will commit, and after death, suffering and tragedy have done their worst, Christ’s purposes still stand. He is the beginning and the end at once. His power must be infinite and his knowledge unsearchable. So sure are his purposes that there is no gap between the beginning and the end. Though from our point of view they are far apart and all history lies between and all human effort and endeavour, yet none of this is significant in determining the outcome of God’s plan.
We reject the idea that Christ is in some way eternally submissive to the Father. That is a great heresy. Statements like the one here run completely contrary to that idea – ‘I am Alpha and Omega.’ That can be said of the Father. It can equally be said of Christ. He is the Almighty, the overall sovereign one. He shares entirely that total authority with the Father. Three persons, one Godhead. There is no superiority, inferiority. Yes, there are Scriptures which tell us that Christ submitted himself to the Father while on earth. Of course it did, because he was our representative. He was behaving as one of us. But eternally there is no such thing as submission of the Son to the Father. He can say ‘I am the Almighty’.
His almighty power is limited, if we may truly call it a limit, only by his other attributes. He cannot act inconsistently with his own holiness or against his own being. It is no limit to his power that he will not create a rock too heavy for himself to lift, or make a square circle. These contradictions belong to the arena of logic and God himself is the author of the laws of logic.