As the title indicates, Responses to religious division considers four responses to religiously motivated conflict from the late sixteenth and early seventeenth centuries. Despite their differences, the authors on whom Constantinidou focuses – Pierre Charron, Justus Lipsius, Paolo Sarpi and King James vi & i – shared several themes as each sought to determine what the role of religion should be following the fragmentation of Christian society. These themes included advocating government control over ecclesiastical matters, distinguishing divinely-ordained religious essentials from humanly-devised externals of religion, associating religious zeal with ignorance and heresy, and maintaining clear divisions between private conviction and public practice. This thematic commonality grows out of the similar challenges that these authors confronted as well as their shared Christian-humanist intellectual milieu.

Constantinidou's first chapter introduces the authors, with special attention to the way in which each was affected by religious conflict. This is followed by four chapters outlining the thought of each in relation to the theme of addressing religious division and the turmoil to which it gave rise. Charron was a French church official who experienced religious turmoil directly, including imprisonment for religious reasons. Troubled by the ways in which religious strife could foster religious apathy as well as sectarianism, Charron laid out principles intended as remedies to religiously-motivated conflict. These include a preference for moderation in religion, a keen awareness of the dangers posed by religious dogmatism, and a conviction that in the name of peace and order governments should oversee outward expressions of religion and subjects should keep dissenting views to themselves. In addition to exploring these principles, the chapter considers ways in which aspects of Charron's work could be read as allowing for religious relativism or even inadvertently legitimising atheism. In facing such accusations, Charron is similar to the other theorists whom this study considers. Like him, they also encountered questions regarding their own religious proclivities and sincerity.

Lipsius developed the distinction between private religious conviction and public confession toward which Charron pointed, a position that fitted well with the protean nature of his own religious identity. Born Catholic, Lipsius held positions at a Lutheran and then a Calvinist university before finally returning to the Catholic fold. Playing up a distinction between the virtues of constancy and prudence, Lipsius sought to secure both interior peace of soul and external peace in the political realm. Echoing Stoic principles, he presented inner constancy of conviction in one's relationship with the divine as key to peace of soul in a turbulent world. In contrast to the stability and moral purity that were hallmarks of constancy, prudence, the virtue for managing political affairs, mixed ‘the honourable’ with ‘the useful’, for example employing deceit as necessary to navigate worldly politics. Like Charron, Lipsius contrasted the clarity of reason, the foundation of constancy, with the opacity of passion that threatened conflict over inconsequential externals of religion. To avoid conflict, political authorities should manage the external face of religion within their realms, and subjects should acquiesce inasmuch as the wise person could maintain internal constancy in one's relationship with God whatever actions prudence may dictate.

As a friar in the service of a Venetian government sporadically embroiled in conflicts with the papacy, Paolo Sarpi was a Catholic who often found himself aligned with Protestants politically, leading some to question where his religious convictions really lay. What is not in doubt, however, is his staunch opposition to papal pretentions to worldly power. Constantinidou focuses on Sarpi's massive history of the Council of Trent in which the friar presents the council as a tragic missed opportunity to reform the Catholic Church and thereby unify Christendom, an opportunity doomed by papal machinations aimed at expanding papal hegemony. Tracing the upheavals of the sixteenth century to papal usurpation of temporal authority, Sarpi echoed Lipsius’ views on the need to clearly distinguish the clerics’ job of caring for souls from the political leaders’ role of overseeing temporal matters, including church councils and other ecclesiastical affairs. He called on temporal authorities to oversee the Church with an eye toward avoiding contentions – marginalising zealots and tolerating variation of opinion with regard to matters of adiaphora.

As king of Scotland and England, James vi & i was in a position not only to theorise and advise but also to take steps to implement lay ecclesiastical supremacy in the interest of peace and order. Like Sarpi, James can more easily be oriented by a pro- versus anti-papal axis than a Protestant versus Catholic one. Convinced that conflicts across the continent could be resolved if politics could be clearly distinguished from religion and clerics would stop meddling in political affairs, James sought to cooperate with sovereigns of all religious stripes to stem papal pretentions to worldly power. Another key dichotomy for James was between reasonable, peaceful religious moderates and irrational, seditious religious zealots – whether ardent papists or fervent Puritans. Echoing many themes familiar from the other authors considered, James added to them an even more elevated vision of the royal office, seeing the king as more than a mere layperson and pointing to Old Testament precedents of kings enforcing orthodoxy as well as ordering religious externals.

Responses to religious division is a solid piece of scholarship, reflecting extensive engagement with both primary texts and secondary literature. Readers looking for a reliable introduction to some Christian humanist responses to religious violence at the turn of the seventeenth century will find it here. This study also confirms the inadequacy of simplistically viewing the religious antagonisms and alliances of early modern Europe through a Protestant-Catholic lens. The four authors considered were more likely to orient themselves along axes of rationalist versus enthusiast, moderate versus zealot, and anti-papal versus pro-papal than Protestant versus Catholic. Responses to religious division will not significantly change the way in which scholars think about early modern humanist responses to religiously-motivated strife, but it does provide useful overviews of four authors who exemplify such responses.