Now if these words in the law, “You shall have dominion over many nations, and no one shall rule over you,” were simply a promise to them of dominion, and if they contain no deeper meaning than this, then it is certain that the people would have had still stronger grounds for despising the promises of the law. Celsus brings forward another passage, although he changes the terms of it, where it is said that the whole earth shall be filled with the Hebrew race; which indeed, according to the testimony of history, did actually happen after the coming of Christ, although rather as a result of God's anger, if I may so say, than of His blessing.
As to the promise made to the Jews that they should slay their enemies, it may be answered that any one who examines carefully into the meaning of this passage will find himself unable to interpret it literally. It is sufficient at present to refer to the manner in which in the Psalms the just man is represented as saying, among other things, “Every morning will I destroy the wicked of the land; that I may cut off all workers of iniquity from the city of Jehovah.” Judge, then, from the words and spirit of the speaker, whether it is conceivable that, after having in the preceding part of the Psalm, as any one may read for himself, uttered the noblest thoughts and purposes, he should in the sequel, according to the literal rendering of his words, say that in the morning, and at no other period of the day, he would destroy all sinners from the earth, and leave none of them alive, and that he would slay every one in Jerusalem who did iniquity.
And there are many similar expressions to be found in the law, as this, for example: “We left not anything alive.”
Source: Against Celsus (New Advent)