My question is not about philosophical views but is focused on theological views.
According to Thomas Aquinas, God is a "subsistent being". He explained the Triune Persons as subsistent relations. And this is where the subject becomes more complex.
My basic understanding is that to describe God as a subsistent being means God is a reality that exists of itself. That seems woefully inadequate so I did some research and found some thoughts from a Welsh Reformed Protestant Theologian:
God IS - that is, God is ETERNAL LIFE, the eternally subsisting being: “Do you not know? Have you not heard? The LORD is the everlasting God, the Creator of the ends of the earth. He will not grow tired or weary, and his understanding no one can fathom” (Isaiah 40:28).
The Bible starts with God – “In the beginning God...” (Genesis 1:1). The knowledge of God is ultimately the sum of all other doctrines. “This is life eternal, that they might know thee the only true God, and Jesus Christ, whom thou hast sent” (John 17:3).
The Bible teaches us about the infinity of God. He is an absolute being; He is not derived from something else nor conditioned by anything else – “I AM that I AM” (Exodus 3:14). God told Moses to say “I AM hath sent me unto you”. God is the ultimate, absolute being. God’s infinity suggests to us that He is the cause of everything else; all existence, all being derives from Him. The infinity of God is emphasised throughout the Bible from beginning (Genesis 1:1) to the end – “Holy, holy, holy, Lord God Almighty, which was, and is, and is to come” (Revelation 4:8).
God is Spirit (John 4:24). He has none of the properties that belong to matter. Because the human mind is too small to span or grasp God or to realise Him, God was made flesh in the incarnation. The revelation of God came in Jesus Christ, the ultimate revelation, the essence of the great act of redemption (Galatians 4:4-5).
Source based on material from ‘God the Father God the Son’ by Dr. Martyn Lloyd-Jones, published 1996. (Chapter 2, pp 15,20 and Chapter 5, pp 47, 53-56 refer)
Is there is a biblical basis for saying God is a subsistent being and what does this tell us about the being of God?
I am not seeking opinions but evidence from a biblical Trinitarian view.