Maimonides Quote

When [Abraham] the "Pillar of the World" appeared, he became convinced that there is a spiritual Divine Being, which is not a body, nor a force residing in a body, but is the author of the spheres and the stars; and he saw the absurdity of the tales in which he had been brought up. He therefore began to attack the belief of the Sabeans, to expose the falsehood of their opinions, and to proclaim publicly in opposition to them, "the name of the Lord, the God of the Universe" (Gen. xxi. 33), which proclamation included at the same time the Existence of God, and the Creation of the Universe by God.

Ch.29 - Guide for the Perplexed (c. 1190) - Part III