This was one of the principal objections raised against Christianity. Antiquity was considered a prime requisite in a religion which claimed to be true, and no reproach was greater than the reproach of novelty. Hence the apologists laid great stress upon the antiquity of Christianity, and this was one reason why they appropriated the Old Testament as a Christian book. Compare, for instance, the apologies of Justin Martyr, Tatian, Athenagoras, Theophilus, Tertullian and Minucius Felix, and the works of Clement of Alexandria. See Engelhardt’s article on Eusebius, in the Zeitschrift für die hist. Theologie, 1852, p. 652 sq.; Schaff’s Church History, Vol. II. p. 110; and Tzschirner’s Geschichte der Apologetik, p. 99 sq.