God said to Moses, “I AM WHO I AM.”
(Exodus 3:14)
Before the mountains were brought forth,
or ever you had formed the earth and the world,
from everlasting to everlasting you are God.
(Psalm 90:2)
In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through him, and without him was not any thing made that was made. In him was life, and the life was the light of men. The light shines in the darkness, and the darkness has not overcome it.
(John 1:1-5)
He is the image of the invisible God, the firstborn of all creation. For byfn him all things were created, in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities—all things were created through him and for him. And he is before all things, and in him all things hold together.
(Colossians 1:15-17)
By self-existence, we refer to that unique attribute of God by which He has existed eternally and will always exist so. Unlike all other things that relate to our existence, God does not owe His being to any other thing. We owe our existence to God. In one sense, our computers owe their existence to Apple or Dell employees and a host of subcontractors. Cupcakes owe their existence to the baker. And our earth owes its existence to God who through whatever means and processes he saw fit, created the world. All events have causes. All creatures have been created. This is true of everything except for God. God is the uncaused cause and the uncreated creator. God did not depend upon anything outside Himself for His existence, nor will He ever depend upon anyone for it.
He is completely and utterly self-existent.