The word theology always means discourse or speech about God. But which God is meant and what does this God do? Plato, in his Republic, assigns theologia to the poets (379a5); by theology he means narratives about the gods and theogonies. Aristotle contrasts the "theologians," who offer mythological explanations of the world, with the "philosophers," or "physiologists," who look for the explanation of things within things themselves. On one occasion he divides "theoretical" philosophy into three parts: mathematics, physics, and theology, this last being identical with "first" philosophy, or metaphysics (Metaphysics 6.1025a). Toward the end of the second century BCE, Panaetius of Rhodes distinguished three kinds of theology and was followed in this by Varro, whom Augustine cites (City of God 6.5): mythological, "natural" or philosophico-cosmological, and civil or political. "Civil theology" or "political theology" referred to the cult of the Caesars.

Among Christians, the first applications...