Pierre Bayle begins his defence of religious toleration with this appeal that the light of nature, or Reason, should be used to settle religious differences and not coercion (1708)

Thus the whole Body of Divines, of what Party soever, after having cry’d up Revelation, the Meritoriousness of Faith, and Profoundness of Mysterys, till they are quite out of breath, come to pay their homage at last at the Footstool of the Throne of Reason, and acknowledg, tho they won’t speak out (but their Conduct is a Language expressive and eloquent enough) That Reason, speaking to us by the Axioms of natural Light, or metaphysical Truths, is the supreme Tribunal, and final Judg without Appeal of whatever’s propos’d to the human Mind. Let it ne'er then be pretended more, that Theology is the Queen, and Philosophy the Handmaid; for the Divines themselves by their Conduct confess, that of the two they look on the latter as the Sovereign Mistress: and from hence proceed all those Efforts and Tortures of Wit and Invention, to avoid the Charge of running counter to strict Demonstration. Rather than expose themselves to such a Scandal, they'l shift the very Principles of Philosophy, discredit this or that System, according as they find their Account in it; by all these Proceedings plainly recognizing the Supremacy of Philosophy, and the indispensable obligation they are under of making their court to it; they’d ne'er be at all this Pains to cultivate its good Graces, and keep parallel with its Laws, were they not of Opinion, that whatever Doctrine is not vouch’d, as I may say, confirm’d and register’d in the supreme Court of Reason and natural Light, stands on a very tottering and crazy Foundation.