The beginning and the end. In the New Testament Book of Revelation, God says, “I am Alpha and Omega,” meaning that he is the beginning and end of all things. In the Greek alphabet, alpha is the first letter and omega is the last. “Alpha and omega” refers to God’s sovereignty and eternal nature.
Who Is the Alpha and Omega?: (Gr. Alpha kai Ōmega)
The phrase "Alpha and Omega" signifies Jehovah's exclusive eternal Godship in Revelation, distinguishing Him from Jesus Christ as the Son.

