The Christian Perspective
God created time (Genesis 1:1; 2 Corinthians 4:18; 2 Timothy 1:9; Titus 1:2; Hebrews 11:3; Jude 1:25).
As the One Who created time, He is inherently atemporal (or omnitemporal depending upon which aspect of His eternality we are emphasizing) (Deuteronomy 33:27; 1 Timothy 1:17; Hebrews 9:14). Given this, He is definitively always the same (Exodus 3:14; Malachi 3:6; James 1:17).
If He is always the same, He cannot cease to exist.