A doctrine of God that states God is not composed of parts. God is simple in that His essence and existence are identical. God is not a composition of individual parts that depend on something outside of themselves in order to function. His essence does not depend on His existence because they are identical. God’s love is not dependent upon His eternality, as if He is only loving so long as He remains eternal. They are the same. Thus, God is simple.

Source: Lexham Survey of Theology, s.v. “God’s Simplicity.”