Leibniz postulates that God can be conceived as proof that God exists. In other words, it is not a question whether God exists: that he can be conceived of means he exists.
Let’s say God is pure love. What pure love ellicits in you is God. It is ellicited, therefore it exists, there for God exists.
This splits people into two: those who believe in substance, and magic, and those who believe in existence only. When it is said that God is pure love, it is not a reference to a substance, but to what is ellicited in you by pure love. When you think about pure love, that is what God is. There is no need to search, nothing is hidden, that very thing is what it is. If a person says that God is pure love, and you say God doesn’t exist, what you are arguing against is the ellicitation of anything in you by pure love. Even if it ellicits doubt or thoughts that there is no pure love, pure love has been ellicited in those thoughts, therefore God has been ellicited in those thoughts. And anything exists, as Descartes said, because thoughts exist, so thoughts exist.
Theology then becomes a very different game. When Leibniz talks about the Grace of God, he is not asking you to argue for or against the existence of a substance God, but for or against whatever the Grace he is describing ellicits. What it ellicits is what Leibniz claims is God. When he describes the way in which everything operates both in an evolutionary stream and with an internal coherence, which he calls God’s design, that because God is perfect the evolutionary stream and his design are perfectly concurrent, there is no burden of proof, but only a thought presented to ponder or not. God is nothing else or other or outside of what is being discussed. That is what God is. And therefore, rather redundantly, God is.
As a separate note, substance exists by the same token and to the same extent. Regardless of your thoughts on substance, it is ellicited, and what is ellicited exists.
I could also have written the title as Rolling Leibniz into Descartes into Parmenides, but thought that might have been rather ambissious to verge with hubris.