These two words are the first and the last letters of the Greek alphabet. The Lord God had applied this same title to himself in Revelation 1:8. Now Jesus Christ applies the title to himself, and immediately adds its significance: he himself is the first and the last
(Revelation 1:17; Revelation 2:8), the beginning and the end.
The three phrases together underscore that all things originate with Jesus Christ and all things culminate in Jesus Christ (Romans 11:36), and so picture the Lord as positioned above all history, in control of all events, and purpose and centre of all that happens. Christ would apply this designation to himself not only because he is God but more specifically because he is the Lamb who could open the seals of the scroll in God’s hand (Revelation 5:9).
13 I am the Alpha and the Omega, the first and the last, the beginning and the end.”