Self-existence means that God is the source of His existence. God is independent of anything or anyone else; He is the source of His own life.
- For just as the Father has life in Himself, even so He gave to the Son also to have life in Himself; - John 5:26
Does the Law of Causation undermine the reality of God’s self-existence? No, it does not. First, causation has limitations. It is limited to those things which have a beginning. Scripture says that God has no beginning.
- Before the mountains were born Or You gave birth to the earth and the world, Even from everlasting to everlasting, You are God. - Psalm 90:2
Second, causation is limited to the created realm. Since God is eternal, He exists outside of the created realm and not beholden to the causation. Third, causation requires that something larger than the universe must exist, which in turn created the universe. The Scripture states that God created the universe.
- In the beginning God created the heavens and the earth. - Genesis 1:1
Fourth, that Causation is a law necessitates the need for a lawgiver. The Scripture states that the Law of Causation is a God-ordained law.
- For every house is built by someone, but the builder of all things is God. - Hebrews 3:4
The one who builds all things is none other than God. God is the only cause, and there are no others.
- I, the Lord, am the first, and with the last. I am He. - Isaiah 41:4
- I am the first and I am the last, And there is no God besides Me. - Isaiah 44:6
- I am the Lord, and there is no other; Besides Me there is no God. I will gird you, though you have not known Me; - Isaiah 45:5
- Remember the former things long past, For I am God, and there is no other; I am God, and there is no one like Me, - Isaiah 46:9
- Louis Berkhof, Systematic Theology (Grand Rapids: Eerdmans, 1941), p. 58.