We, then, alone are without crime. Is there ought wonderful in that, if it be a very necessity with us? For a necessity indeed it is. Taught of God himself what goodness is, we have both a perfect knowledge of it as revealed to us by a perfect Master; and faithfully we do His will, as enjoined on us by a Judge we dare not despise. But your ideas of virtue you have got from mere human opinion; on human authority, too, its obligation rests: hence your system of practical morality is deficient, both in the fullness and authority requisite to produce a life of real virtue.
Man's wisdom to point out what is good, is no greater than his authority to exact the keeping of it; the one is as easily deceived as the other is despised. And so, which is the ampler rule, to say, “You shall not kill,” or to teach, “Be not even angry?” Which is more perfect, to forbid adultery, or to restrain from even a single lustful look? Which indicates the higher intelligence, interdicting evil-doing, or evil-speaking? Which is more thorough, not allowing an injury, or not even suffering an injury done to you to be repaid?
Though withal you know that these very laws also of yours, which seem to lead to virtue, have been borrowed from the law of God as the ancient model. Of the age of Moses we have already spoken. But what is the real authority of human laws, when it is in man's power both to evade them, by generally managing to hide himself out of sight in his crimes, and to despise them sometimes, if inclination or necessity leads him to offend? Think of these things, too, in the light of the brevity of any punishment you can inflict— never to last longer than till death.
On this ground Epicurus makes light of all suffering and pain, maintaining that if it is small, it is contemptible; and if it is great, it is not long-continued. No doubt about it, we, who receive our awards under the judgment of an all-seeing God, and who look forward to eternal punishment from Him for sin—we alone make real effort to attain a blameless life, under the influence of our ampler knowledge, the impossibility of concealment, and the greatness of the threatened torment, not merely long-enduring but everlasting, fearing Him, whom he too should fear who the fearing judges,— even God, I mean, and not the proconsul.
Source: The Apology (New Advent)