In his much discussed lecture at Regensburg University on September 12, 2006, Pope Benedict underscored the crucial importance of Hellenistic philosophy in the development of early Christian theology. That engagement with philosophy is indeed of lasting importance for Christian theology. It is grounded not only in the teaching about the universal logos found in the Gospel of John, which was rightly emphasized by Benedict, but also in the thought of the apostle Paul. It is true that Paul had harsh words for the "worldly wisdom" that rejected the message of the crucified and risen Son of God. But he also affirmed that, by the exercise of clear reason, human beings know of the one God--the one God who is creator of the world and who revealed himself in Jesus Christ, as proclaimed by the apostles. (See Romans 1 and 2, and Acts 17.)
Greek philosophy was in search of the true nature of the divine, which led to the conclusion that there can be only one God. The one God of the People of Israel, however, who was also the God of Jesus and the early Christians, was viewed by the Greeks as an alien deity of an alien people and so could not command their allegiance. It was therefore necessary to make the argument that the God of Israel is, in fact, the one God conceived by the philosophers. This contention was essential to the plausibility of both Jewish and Christian witness in the Hellenic world.
For Christian theology, making this claim about the identity of the one God was not just an early instance of cultural adaptation--a cultural adaptation that could, in different times and different places, be succeeded and replaced by other forms of "inculturation." The affirmation that the God of Israel and the God of the philosophers is the one and same God--an affirmation that entails the reception by Christian theology of the philosophical argument for the one true God--is a constitutive and permanent feature of Christian faith.
This is by no means a peculiarly Roman Catholic understanding. In his large catechism, Martin Luther says that God the Father, as proclaimed by Jesus, is the only true God "because nobody else could create heaven and earth." In this he is entirely in accord with early Christian thinkers and their use of philosophical theology. To be sure, Luther was sharply critical of what he viewed as the dominance of Aristotle in Scholastic theology, but he did not reject the entire tradition of Christianity's incorporation of Greek philosophy. He did not, for instance, reject Platonism, which, we do well to remember, had been the primary influence in Christian theology until the thirteenth …