Both New Testament writers and postbiblical Christians sharply opposed the God of their faith to the many gods of popular religion. In doing so they joined not only Jews but also most thoughtful pagans, who believed in one God beyond the many. Because the reality of the one God was not in doubt, arguments for God's existence in that era were unimportant.

There was, however, during the early centuries of the Christian era a great divide. On one side were those classical religious thinkers who continued to reflect on God in strictly philosophical ways, trusting their reason to suffice. This tradition reached its apex in Neoplatonism. On the other side were those who accepted the authority of Jewish (supplemented later by Christian or Islamic) scriptures, correlating the ideas found there with the fruits of reason. The great Alexandrian Jew Philo, a contemporary...