Dialogue of Justin, Philosopher and Martyr with Trypho a Jew

If you remain in that mode of philosophy, and live blamelessly, a hope of a better destiny were left to you; but when you have forsaken God, and reposed confidence in man, what safety still awaits you? If, then, you are willing to listen to me (for I have already considered you a friend), first be circumcised, then observe what ordinances have been enacted with respect to the Sabbath, and the feasts, and the new moons of God; and, in a word, do all things which have been written in the law: and then perhaps you shall obtain mercy from God.