When Nicodemus approached Jesus under cover of night (John 3), he did so to keep from being seen with someone accused of taking liberties with Jewish tradition and morality. Both Nicodemus’s strategy and the associations he sought to avoid took on new forms in early modern Europe. Nicodemism was the practice of hiding one’s beliefs, usually to evade persecution. Libertinism included various forms of ethical indifference. Nicodemism and libertinism in the Reformation era are best understood in relation to the period’s profound cultural changes. A proliferation of new religious confessions in early modern Europe put many believers at odds with their communities. The resulting fluidity of religious identity meant that what one practiced did not always correspond with what one believed. More urgently, landing on the wrong side of belief could have disastrous, even deadly, consequences. The stakes were high at a time when religious pluralism was widely viewed as impurity that put a society under threat of divine judgment. Borders dividing mainstream from deviant religion could change quickly, so that a person found herself having to either prove she belonged or hide that she did not. Widespread persecution forced migration and exile upon those who could no longer worship according to their beliefs. Yet not everyone had the luxury of leaving for friendlier environs. Traditions of martyrdom and accusations of crypto-religion emerged within Catholic, Protestant, and radically reformed communities alike.