Montesquieu

If there is a God…he must necessarily be just; for if he were not, he would be the most wicked and imperfect of all beings…. Men commit unjust acts because it is to their advantage to do so and because they prefer their own contentment to that of others. They always act from selfish motives: no man is evil gratuitously: there must be a determining cause, and that cause is always selfishness. But God cannot possibly commit an unjust act: once we assume that he perceives what is just he must of necessity act accordingly, for since he is self-sufficient and in need of nothing, he would otherwise be the most wicked of beings, since he has no selfish interests. Thus, if there were a God, we would still be obliged to venerate justice, that is, we should do everything possible to resemble that being of whom we have such an exalted notion and who, if he exists, would necessarily be just. — from Persian Letters, #83

Charles-Louis de Secondat, baron de La Brède et de Montesquieu (1689–1755) was a French philosopher of the French Enlightenment. His most important contribution to modern thought is his theory of the separation of powers, from which the American founders drew their schema for the three branches of government as outlined in the U.S. Constitution. Although considered mainly a political philosopher, Montesquieu drew his ideas from ancient history and popularized the idea of history being driven by culminating ideas instead of dynamic individuals.