Early Christian polemicists such as Clement of Alexandria, Justin Martyr, Irenaeus of Lyons, and Tertullian all attacked Gnosticism as 'heresy' and until the 20th Century virtually nothing was known about it except in the distorted texts they had written. Their purpose was to construct the boundaries between what later became 'orthodox' or 'catholic' Christianity in opposition to Judaism, paganism and carious Christian 'heresies'. Until the fourth and fifth centuries, however, when Christianity became the state religion of the Roman Empire under "the guiding influence of the Christian emperors" like Constantine and Theodosius, Christian 'orthodoxy' was still fluid and in dispute. Only because of the power of the Roman state did Christianity become a "monolithic unity" that had not existed before and redefined "manifold ancient religious practices into three mutually exclusive groups: Jews, Christians and pagans (King 22). Early Christian polemicists deliberately exaggerated the differences between these groups and minimized the similarities, although for the first three centuries of Christianity no commonly recognized hierarchy or Scriptural canon existed. For the early Christian apologists and polemicists, the 'heretics' were not real Christians even though "there was no predetermined orthodoxy that was simply there, waiting to be more carefully defined" (King 25). In the end, the 'orthodox' Christians won the battle and their words were preserved, which was not the case with their opponents.
The Didache was basically an instruction manual used in the early Christian churches in Asia Minor in the first and second centuries, although no complete copy of it was thought to have survived until a Greek manuscript was discovered in Istanbul in 1873. Although its theology falls well within the later 'orthodox' Christian tradition, it was not included in the Biblical canon. It copied Jesus in incorporating much of the Jewish law, and had a list of prohibited acts such as murder, adultery, theft, corruption of boys, magic, divination, astrology, and coveting the goods of others. All of these could be found in many other Christian texts of the time and later, and the Didache describes them as the way of death (Milavec 5). In addition, it borrowed from the Sermon on the Mount, calling on Christians to be gentle, kind, patient, long-suffering, to share with the needy, give generously to charity, and to avoid anger, hatred or lust. This was the way of eternal life (Milavec 11). All Christians were required to confess their failings before the entire church, although they were to be rebuked in a gentle way (Milavec 15). Baptism would be by immersion in water in the name of the Father, Son and Holy Spirit, while communion would be taken with both bread and wine, giving thanks "for the life and knowledge which you revealed to us through your servant Jesus" (Milavec 23). In addition, Christians were required to say the Lord's Prayer three times a day, looking forward to the establishment of the Kingdom of God on earth. Finally, the Didache refers to the lasts days and the end of the world, which will be a time of war, violence and lawlessness and the appearance of a "world-deceiver as a son of God" who would do miracles and deceive the many. Those Christians who remained faithful to the end, however, would be saved when Christ returned again (Milavec 39).
Early Christians struggled with defining their own identity in opposition to Judaism and paganism, and also against other Christians whose teachings were regarded as heretical. Like all people in the ancient world, they "located the truth of their beliefs and practices, and established their identity, by appeal to origin, essence and purity," and the connection to Judaism gave them an ancient and venerable theology (King 37). At the same time, they also defined Judaism "with suppressed truth now gone awry, and paganism with error" (King 38). Christianity did not define itself as a matter of individual choice, which hardly existed in the ancient world, but as part of a "tradition and way of life" (King 39). Judaism provided Christians with a respected past, but they also had to decide how much of the Jewish law and Scriptures could be incorporated for their own purposes. Paul had argued that Israel now included all Gentiles from 'the nations' who accepted Christ, and that they would no longer have to follow Jewish laws and dietary practices, while Matthew declared Jesus to be the fulfillment of the law and prophets (King 41).
In the third and fourth centuries, the distinctions between Judaism and Christianity were not necessarily clear and absolute, since Jewish Christians still attended synagogues, practiced circumcision and adhered to Jewish dietary laws. They did not believe that following Christ required "a definite break with Judaism" (King 41). One second century Gnostic text, the Epistle of Barnabas, called for a complete break with Judaism because the Jews had broken their covenant with God, while the Gnostic Gospel of Mary and the Gospel of Truth hardly mentioned the Jewish Scriptures at all (King 44). Justin Martyr also thought that Jesus had fulfilled the prophecies of the Jewish Scriptures, but his opponents claimed that these were also a mixture of truth and error. In his tract Dialogue with Trypho the Jew in 160 AD, Justin attempted to create "a Judaism useful for Christian polemics," when he argues against Trypho for denying that Jesus was God and calling Christians 'heretics' for violating dietary laws and not celebrating Jewish holidays (King 42). Justin countered that the Jews had broken their covenant with God by rejecting Jesus and had been punished with the destruction of the Jerusalem Temple. He was emphatic that "God had rejected Israel and offered universal salvation to the Gentiles," although he also argued for incorporation of Moses, the Ten Commandments and Jewish monotheism and ethics into Christianity (King 43).
Tertullian also insisted that Christianity should be rooted in Judaism and had to avoid any admixture with Greco-Roman philosophy, but neither he nor Justin could point to a commonly accepted version of the Christian Bible, which did not yet exist in second century. This remained "an open question for many others" at the time as well, as did the question of what 'orthodox' Christianity truly meant (King 28). The writers of the Didache also opted for partial and selective incorporation of Jewish law, but did not mention the synagogue, circumcision or dietary laws (King 42). Marcion and the Sethite Gnostics were particularly hostile to the Jewish Scriptures, arguing that the Creation in Genesis was really "the work of an inferior creator God" as opposed to the Higher Being revealed by Jesus and Paul (King 45). They did not believe that Adam and Eve had committed original sin by discovering the knowledge of good and evil, since this had allowed them "to perceive that the creator of the world is but a jealous and vengeful pretender" (King 45). In the Gnostic Epistle to Flora in the second century, Ptolemy classified the Jewish Scriptures into three types, which originated either with God, Moses or the Jewish elders. Only those parts that were from God, such as the Ten Commandments, were pure and perfect enough to be incorporated into the Christian Bible, while other parts like the Jewish "eye for an eye" had been corrected with the command of Jesus to "turn the other cheek" (King 46). Ptolemy also agreed that Jesus has revealed the True God to humanity, not the inferior one who created the material world. One of the Nag Hammadi texts, The Testimony of Truth, claimed that even the apostles "mistook the world creator for the True God" (King 47).
Early Christian polemicists like Irenaeus of Lyons attacked the Gnostics for these ideas that the creator God was false, the material world was evil or that Jesus did not have a physical body. In his Expose and Overthrow of What is Falsely Called Knowledge, Irenaeus claimed that the Gnostics did not regard Jesus as a savior who had taken on the sins of the world but brought salvation only through this type of "knowledge revealed only to them" (King 27). In Against the Heresies, he "set a pattern for attacking one's opponents that would persist to the present day," when he attempted to show that that Gnostics were "inspired by evil spirits" (King 31). He traced their origins to Simon Magus (Simon the Samaritan) and his wife Helen, who he regarded as followers of the Devil sent to bring chaos and disorder into the world. Tertullian blamed Gnostic 'heresy' on the influence of Plato, Zeno, Stoicism and other elements of Greek philosophy, especially in their belief that Jesus had no physical body and the material world was inferior and evil. He noted that Paul had also warned about the dangers of Athenian influence on Christianity, although ironically Tertullian was also condemned as a heretic (King 33). All of this became the standard 'orthodox' Christian view of the Gnostics that has come down to the present, along with the idea that rejected the authority of the apostles and the bishops…