This article considers the extent to which the liberal nation-state ought to accommodate religious practices that contravene state law and to incorporate religious discourse into public debate. To address these questions, the article develops a liberalism of sincerity based on John Locke's theory of toleration. On such an account, liberalism imposes a duty of sincerity to prevent individuals from consenting to a regime that exercises control over matters of core concern such as faith, religion, and conscience. Liberal theory grounds the legitimacy of the state in the consent of the governed, but consenting to an intolerant regime is illegitimate because it empowers government to demand insincere conduct. Thus, demanding that citizens pursue sincerity ensures that they do not consent away their individual liberties in exchange for promises of security and orderliness. The focus on sincerity also reorients the value that liberalism places on religious pluralism. Although many liberal theorists have proposed that religious pluralism is valuable because it provides individuals with a range of choices on how to live the good life, such theories provide little reason to promote and protect any particular religion. Indeed, if religions are important only because of the range of choice they provide, then the only concern of liberalism is to maintain enough religions so as to provide a meaningful range of options for how to live the good life; conversely, there is no reason to provide accommodations for any particular religion to aid its survival. By contrast, a liberalism of sincerity impels the liberal nation-state to widen the protections afforded to the expressions of sincerity, such as religious conduct and religious discourse. Because religious conduct and religious arguments flow from an individual's commitment to sincerity, liberalism should provide broad protection for such religious activity in order to enable citizens to pursue sincerity. This article considers the extent to which the liberal nation-state ought to accommodate religious practices that contravene state law and to incorporate religious discourse into public debate. To address these questions, the article develops a liberalism of sincerity based on John Locke's theory of toleration. On such an account, liberalism imposes a duty of sincerity to prevent individuals from consenting to a regime that exercises control over matters of core concern such as faith, religion, and conscience. Liberal theory grounds the legitimacy of the state in the consent of the governed, but consenting to an intolerant regime is illegitimate because it empowers government to demand insincere conduct. Thus, demanding that citizens pursue sincerity ensures that they do not consent away their individual liberties in exchange for promises of security and orderliness. The focus on sincerity also reorients the value that liberalism places on religious pluralism. Although many liberal theorists have proposed that religious pluralism is valuable because it provides individuals with a range of choices on how to live the good life, such theories provide little reason to promote and protect any particular religion. Indeed, if religions are important only because of the range of choice they provide, then the only concern of liberalism is to maintain enough religions so as to provide a meaningful range of options for how to live the good life; conversely, there is no reason to provide accommodations for any particular religion to aid its survival. By contrast, a liberalism of sincerity impels the liberal nation-state to widen the protections afforded to the expressions of sincerity, such as religious conduct and religious discourse. Because religious conduct and religious arguments flow from an individual's commitment to sincerity, liberalism should provide broad protection for such religious activity in order to enable citizens to pursue sincerity.