The testimony rendered to the authenticity of the Gospels by the heretics who flourished between A.D. 130 and 170 is of importance. At the beginning of this period, Basilides, the {13} great Gnostic of Alexandria, who tried to replace Christianity by a semi-Christian Pantheism, appears to have used Matt., Luke, and John. The fact that they contain nothing which really supports his peculiar tenets, forms an argument which shows that the genuineness of these documents was then too well established for it to be worth his while to dispute it. Marcion, whose teaching was half Gnostic and half Catholic, endeavoured to revive what he imagined to be the Christianity of St. Paul, whom he regarded as the only true apostle. He believed that Judaism was the work of an inferior god, and he therefore rejected the whole of the Old Testament, and retained only the Gospel written by St. Luke, the friend of St. Paul, and ten of St. Paul's Epistles. Modern writers have sometimes urged that Marcion's list of New Testament books proves that all other parts of the New Testament were regarded as doubtful about A.D. 140. But it is quite evident that Marcion, unlike those Gnostics who adapted uncongenial books to their own systems by means of allegorical explanations, cut out the books and verses which would not correspond with his own dogma. In spite of his pretended fidelity to St. Paul, he mutilated not only St. Luke's Gospel, but even the Epistle to the Galatians. So whereas it is certain that he used our Luke, there is no indication to show that he did not admit that the other Gospels were really the work of the writers whose names they bear.