The earliest followers of Jesus were apocalyptic Jewish Christians. The early Christian groups were strictly Jewish, such as the Ebionites and the early Christian community in Jerusalem, led by James, the brother of Jesus. According to , they described themselves as "disciples of the Lord" and "of the Way", and according to a settled community of disciples at Antioch were the first to be called "Christians". Some of the early Christian communities attracted gentile God-fearers, who already visited Jewish synagogues. The inclusion of gentiles posed a problem, as they could not fully observe the Halakha. Saul of Tarsus, commonly known as Paul the Apostle, persecuted the early Jewish Christians, then converted and started his mission among the gentiles. The main concern of Paul's letters is the inclusion of gentiles into God's New Covenant, deeming faith in Christ sufficient for righteousness. Because of this inclusion of gentiles, early Christianity changed its character and gradually grew apart from Judaism and Jewish Christianity during the first two centuries of the Christian Era. The fourth-century church fathers Eusebius and Epiphanius of Salamis cite a tradition that before the destruction of Jerusalem in AD 70 the Jerusalem Christians had been miraculously warned to flee to Pella in the region of the Decapolis across the Jordan River.