In his endeavours against pagan polytheism, he first clarified the Christian concept of God, particularly the notion familiar among the Hellenistic Jews of Alexandria: the historical revelation of God which the Jews had received; the advent of the Son of God which had been prophesied and which, for the Christians, had taken place in Christ. Tertullian, however, had to explain two things if he was not to give assistance to heathen polytheism: how this Son of God does not, as the Son, destroy the singleness of God and how it happened that he could become man in a way different from the heathen mythologies.