Given that the early Ancient Greeks were not Jews or Christians, and that most medieval theology heavily rehashes Plato and Epictetus, I'm not sure why anyone would suggest the Bible, rather than classical Greek thought, is the foundation of the West's beliefs.

Furthermore, even if there are no serious defenses of moral realism without a mystical metaphysics, that doesn't entail anything. These values were around in humanity long before monotheism and its predecessors.