But since nothing belonging to human nature is permanent, this polity also must gradually be corrupted and changed. And Providence, having remodelled their venerable system where it needed to be changed, so as to adapt it to men of all countries, gave to believers of all nations, in place of the Jews, the venerable religion of Jesus, who, being adorned not only with understanding, but also with a share of divinity, and having overthrown the doctrine regarding earthly demons, who delight in frankincense, and blood, and in the exhalations of sacrificial odours, and who, like the fabled Titans or Giants, drag down men from thoughts of God; and having Himself disregarded their plots, directed chiefly against the better class of men, enacted laws which ensure happiness to those who live according to them, and who do not flatter the demons by means of sacrifices, but altogether despise them, through help of the word of God, which aids those who look upwards to Him.
And as it was the will of God that the doctrine of Jesus should prevail among men, the demons could effect nothing, although straining every nerve to accomplish the destruction of Christians; for they stirred up both princes, and senates, and rulers in every place—nay, even nations themselves, who did not perceive the irrational and wicked procedure of the demons—against the word, and those who believed in it; yet, notwithstanding, the word of God, which is more powerful than all other things, even when meeting with opposition, deriving from the opposition, as it were, a means of increase, advanced onwards, and won many souls, such being the will of God.
And we have offered these remarks by way of a necessary digression. For we wished to answer the assertion of Celsus concerning the Jews, that they were “fugitives from Egypt, and that these men, beloved by God, never accomplished anything worthy of note.” And further, in answer to the statement that “they were never held in any reputation or account,” we say, that living apart as a “chosen nation and a royal priesthood,” and shunning intercourse with the many nations around them, in order that their morals might escape corruption, they enjoyed the protection of the divine power, neither coveting like the most of mankind the acquisition of other kingdoms, nor yet being abandoned so as to become, on account of their smallness, an easy object of attack to others, and thus be altogether destroyed; and this lasted so long as they were worthy of the divine protection.
But when it became necessary for them, as a nation wholly given to sin, to be brought back by their sufferings to their God, they were abandoned (by Him), sometimes for a longer, sometimes for a shorter period, until in the time of the Romans, having committed the greatest of sins in putting Jesus to death, they were completely deserted.
Source: Against Celsus (New Advent)