Justin Martyr, Second Apology 9

I will answer briefly so that no one can repeat the charge leveled by those who pass for philosophers: that our teaching on the eternal fire awaiting the unrighteous is nothing but fable and scare‑tactic, and that we urge virtue only from fear, not because it is good and pleasing in itself. If that charge were true, then either God does not exist, or He exists but cares nothing for humanity; virtue and wickedness would be empty names, and, as I have already said, lawmakers would be punishing transgressors of good laws unjustly. But those lawmakers and their Father are not unjust; they teach through the Word that we should do the same righteous things, so those who agree with them are not unjust either.

If someone objects by pointing to the diversity of human laws — claiming that what one people calls good another calls shameful, and vice versa — let him also hear the answer to that objection. We know that wicked angels have established laws that mirror their own wickedness, and that people who become like them take pleasure in those laws. Right reason, passing over all opinions, does not prove that every doctrine is good; it distinguishes the bad from the good. Therefore the same and similar things will be said to such objectors, and at greater length if need be. For now, I return to the matter at hand.