When revealing the end of human history, God introduces Himself to the seven churches as the eternal Being (of the past, present
and future), the beginning and end as well as the first and last:
"I am the Alpha (ἄ) and the Omega (ō)," says the Lord God, "who is and who was and who is to come, the
Almighty." (Rev 1:8).
This attribute of God establishes Him as unique, supreme, and above all other beings: God is both timeless and everlasting.
He is timeless, because He existed outside of time and created time during Creation
He is everlasting, because He also exists during every point of time while interacting with human beings.
This corroborates Jesus' promise to Believers of an everlasting life with God (John 3:16;
And the testimony is this, that God has given us eternal life, and this life is in His Son. He who has the Son
has the life; he who does not have the Son of God does not have the life. These things I have written to you who believe in the name of
the Son of God, so that you may know that you have eternal life. (1 John 5:11-13)
To learn more, see:
God is Eternal