In the Republic, Plato compares the Idea of the Good to the sun, as the supreme cause of all knowledge and existence. As the multiplicity of individuals is unified in the respective Ideas, in the same manner the multiplicity of Ideas is unified in the Idea of the Good. Hence in the Platonic system the Idea of the Good is the supreme reality on which all other ideas and all ethical, logical and aesthetic values of the sensible world depend. The Idea of the Good is the reality through which the world of becoming is made possible and rational. Thus it is truly the god of Plato.
But the Idea of the Good has neither personality nor the power of creating. According to Plato, Demiurge is the divine artificer which forms the heavens and the earth by successive infusions of souls. Demiurge, however, cannot be identified with God, for if he is superior to matter, he is inferior to ideas, which furnish the model he uses to arrange matter and transform Chaos in the visible world.
Since God is identified with the impersonal Idea of the Good, which lacks any activity with reference to nature and man. He can be attained only by reason, and the cult of reason is due Him.
Regarding popular religion, Plato is opposed to anthropomorphism. So greatly is he opposed to it that, as we have seen, he wished to banish the poets, not excepting Homer, from the ideal state on account of the fantastic and immoral myths with which they represent the gods. He is not opposed, however, to a form of astral polytheism in which a multitude of gods subject to Demiurge animates the stars and the cosmic universe. These are the visible gods which Plato wishes to substitute for rough and uncouth Grecian mythology.
Jonathan Dolhenty, Ph.D. For more on classic philosophers from Dr. Dolhenty and many others, visit The Radical Academy: a Project of the Center for Applied Philosophy and The Moral Liberal.