Goodness is not a quality nor a habit added to God’s essence, but is instead a nature. Goodness is itself the essence of God. He is not first God and then good, but He is good as He is God. His essence—being one and the same—is formally and equally both God and good. Αυιάγαθον, “good of Himself,” was one of the names the Platonists gave Him. He is essentially good in His own nature, and not by any outward action…….
If God were not good by His essence, He could not be eternally good nor the first good…… God’s goodness must be infinite with no limits. The practice of God’s goodness may be limited by Himself, but His goodness—the principle—cannot be circumscribed or limited. Since His essence is infinite and His goodness is not distinguished from His essence, His goodness must be infinite also.
From the book “Boundlessly Good”