The Greeks’ gods were never meant as representations of goodness and were uniformly pretty awful moral avatars – petty, often pitiless, given to jealousies. Zeus came into a universe already created, so not all powerful either. The Greeks never had a Devil, only monsters – Medusa, Cerberus, the Minotaur. The Christian conception of the moral universe and of God is fundamentally different. First, it is monotheistic. Mary and the Saints and angels have intercessory power but that’s all. We are commanded to love Him and each other. No such commands existed for the Greeks. They owed the gods fealty and sacrifices. They needed to appease them. They never depended upon them for moral guidance.
Their conception of good and evil was personal and familial (with a broad interpretation of family to also include extended kinship groups and the polis of one’s native city-state as well). For example, all of the City States were guilty of what we would call atrocities against other City-States – the enslavement of women and children, the mass murder of prisoners and sometimes all the inhabitants of a captured city, including infants.
The gods often enabled what we would describe as evil. In Euripides Medea, Helios, the Sun God provides Medea an escape from justice in a winged chariot, the bodies of her murdered children arrayed at her feet. Odysseus never pays a price with men or with the gods for abandoning Philoctetes on an island because he had a wound that was physically repulsive – this action done to a comrade, a fellow warrior. Three gods, Apollo, Hermes and Athena, protect Orestes, murderer of his mother, from the Furies.
In spite of the hypocrisies and too often barbarous action of institutional Christianity, one might make the argument that the Western idea of a universal criteria for good and evil began with Christ and the New Testament and entered a wider philosophical appreciation with the philosophers of the Enlightenment.
