Some names of God, even though they sound Christian and are used by some Christians, actually have non-Christian origin and have Christian heretical background. Good God is one of such names.
Good God appears in The Love Letters of Abelard and Heloise and Good One is spoken in the Liturgy of St. John Chrysostom. Today, Good God in English has become an oath expressing surprise, shock, frustration, or annoyance.
That being said, the origin of Good God is Platonic. That is how Plato called God. Later Platonists also called God by the name of Good. The Neo-Platonist Proclus tells in Metaphysical Elements that “the adding of any thing else to The Good is to diminish it by the addition, making it a certain or particular good instead of that which is simply good.”
This name for God is also used by Hermetists. Hermes Trismegistus explains in To Asclepius that Good is God because he gives all things and receives naught, and was analyzed in details in the hermetic script In God alone is Good and Elsewhere Nowhere . This text underlines that Good is God himself. Good Diamon is another way how Hermetists emphasized this name of God. It appears in About the Common Mind. Hermes Trismegistus explains that Good Diamon is the First-born God.
Good is the way how many early Gnostic Christians considered and described God from the New Testament in contrast from God from the Old Testament, who is no Good. Marcion of Sinope, born at the end of the First century, rejected the Old Testament completely, and also most of the New Testament, but considered Jesus Christ to be the son of Good God.
Later Hermetics, like Ficino, also talk about God as infinite goodness. Among the Christians, mystics liked using this name of God. So, for example, Leonardus Lessius (1554-1623) tells in his book The Names of God that God is so called because he is the source of all goodness and because he is infinitely above all good that a created mind can conceive. Good is also the 22nd God’s name according to Kircher and the 22nd quantity key according to Bardon. It is linked to Jeiaiel.
Image: An image of God the Father by Julius Schnorr, 1860.