Theology might justly be defined the _science of contradictions_. Every religion is only a system, invented to reconcile irreconcilable notions. By the aid of habit and terror, man becomes obstinate in the greatest absurdities, even after they are exposed in the clearest manner. All religions are easily combated, but with difficulty extirpated. Reason avails nothing against custom, which becomes, says the proverb, _a second nature_. Many persons, in other respects sensible, even after having examined the rotten foundation of their belief, adhere to it in contempt of the most striking arguments. Whenever we complain of religion, its shocking absurdities, and impossibilities, we are told that we are not made to understand the truths of religion; that reason goes astray, and is capable of leading us to perdition; and moreover, that _what is folly in the eyes of man, is wisdom in the eyes of God_, to whom nothing is impossible. In short, to surmount, by a single word, the most insurmountable difficulties, presented on all sides by theology, they get rid of them by saying, these are _mysteries_! 111. What is a mystery? By examining the thing closely, I soon perceive, that a mystery is nothing but a contradiction, a palpable absurdity, a manifest impossibility, over which theologians would oblige men humbly to shut their eyes. In a word, a mystery is whatever our spiritual guides cannot explain. It is profitable to the ministers of religion, that people understand nothing of what they teach. It is impossible to examine what we do not comprehend; when we do not see, we must suffer ourselves to be led. If religion were clear, priests would find less business. Without mysteries there can be no religion; mystery is essential to it; a religion void of mysteries, would be a contradiction in terms. The God, who serves as the foundation of _natural religion_, or _deism_, is himself the greatest of mysteries. 112. Every revealed religion is filled with mysterious dogmas, unintelligible principles, incredible wonders, astonishing recitals, which appear to have been invented solely to confound reason. Every religion announces a hidden God, whose essence is a mystery; consequently, the conduct, ascribed to him, is no less inconceivable than his essence. The Deity has never spoken only in an enigmatical and mysterious manner, in the various religions, which have been founded in different regions of our globe; he has everywhere revealed himself only to announce mysteries; that is, to inform mortals, that he intended they should believe contradictions, impossibilities, and things to which they were incapable of affixing any clear ideas.