Such skepticism often acted as bulwark for Voltaire’s defense of liberty since he argued that no authority, no matter how sacred, should be immune to challenge by critical reason. Voltaire’s views on religion as manifest in his private writings are complex, and based on the evidence of these texts it would be wrong to call Voltaire an atheist, or even an anti-Christian so long as one accepts a broad understanding of what Christianity can entail. But even if his personal religious views were subtle, Voltaire was unwavering in his hostility to church authority and the power of the clergy. For similar reasons, he also grew as he matured ever more hostile toward the sacred mysteries upon which monarchs and Old Regime aristocratic society based their authority. In these cases, Voltaire’s skepticism was harnessed to his libertarian convictions through his continual effort to use critical reason as a solvent for these “superstitions” and the authority they anchored. The philosophical authority of romanciers such as Descartes, Malebranche, and Leibniz was similarly subjected to the same critique, and here one sees how the defense of skepticism and liberty, more than any deeply held opposition to religiosity per se, was often the most powerful motivator for Voltaire.