In “The Religious Enlightenment,” a book published in August by Princeton University Press, Dr. Sorkin aims at nothing less than “to revise our understanding of the Enlightenment.”

Building on recent scholarship highlighting the ideological and geographical diversity of 18th century thought, Dr. Sorkin posits a specifically religious Enlightenment that not only shared characteristics across confessional lines as well as national borders — hence his book’s subtitle, “Protestants, Jews, and Catholics from London to Vienna”— but also “may have had more influential adherents and exerted more power in its day than either the moderate or the radical version of the Enlightenment.”

Leading thinkers of this religious Enlightenment, he explains, sought a “reasonable” faith that was answerable to contemporary science and philosophy, and not grounded merely on dogmatic authority, pure emotion or fascination with the miraculous.

These thinkers agreed with deists that there was a kind of “natural religion,” basic truths about God and morality accessible to reasoning people. Natural religion was not a rival or alternative, however, to revealed religion. It was a prelude, a necessary but insufficient foundation for belief. Without a further belief resting on revelation, reason was likely to end in skepticism and immorality.

To interpret this revelation, a.k.a., the Bible, leaders of the religious Enlightenment generally employed the principle of “accommodation”: the conviction that God had “accommodated” humanity’s limited understanding by using language, imagery and stories suited to particular ages and cultures. The transcendent truths of sacred texts had to be extracted from what was historically conditioned.

The standard-bearers of the religious Enlightenment championed religious toleration and the freedom of religious minorities, although they stopped well short of calling for state neutrality in religious affairs.

They believed in established churches that fostered public virtue through moral instruction and official ritual without coercing dissenters. Like their secular counterparts, they were eager to put in place their reforming ideas through the power of enlightened monarchs.

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Also like their secular counterparts, the leading figures of the religious Enlightenment were active in the newly emerging public sphere, the so-called “republic of letters.” These religious writers shared and shaped ideas through wide-reaching networks of acquaintance, correspondence and publishing.

They were engaged with secular concerns; wrote about history, philosophy, politics and current affairs; and crossed intellectual paths — or swords — with Enlightenment giants like Montesquieu, Voltaire, d’Alembert and Rousseau.

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Dr. Sorkin’s book is something of a sandwich. In the opening and concluding chapters, he sets out his programmatic proposal for restoring religion to the conventional portrait of the Enlightenment. In between are detailed studies of six representatives of the religious Enlightenment.

William Warburton was a learned and pugnacious thinker within the Church of England. Jacob Vernet reigned over Calvinism in Geneva. The Lutheran theologian Siegmund Jacob Baumgarten was praised by Voltaire as “the jewel in the crown of German scholarship.”

Moses Mendelssohn, a paragon of Enlightenment Judaism, translated the Pentateuch into German, and advocated Jewish emancipation. Joseph Valentin Eybel promoted Catholic reform under the Hapsburgs. Adrien Lamourette, Catholic priest and political pamphleteer, was elected bishop of Lyons in the Constitutional Church of the French Revolution.

These are hardly household names, not even in households boasting advanced degrees in history or theology. And these are formidable chapters that may challenge even some scholarly specialists, so dense are the references to religious politics and theological “isms” as the author works his way from Protestantism (in Anglican, Calvinist and Lutheran flavors) to Judaism and Catholicism and across the continent from Hanoverian England to Hohenzollern Prussia and Hapsburg Austria.

Dr. Sorkin acknowledges that he has focused on “second-rank figures,” however prominent in their day, although being second rank may make them more representative rather than less so.

He stoutly rebuts the assertion that these thinkers were not “sincere believers and apologists” but “trimmers” looking for a comfortable perch partway down the slippery slope to unbelief. It is a charge, Dr. Sorkin believes, resting on the assumption that the only viable alternatives were the existing orthodoxies or total secularization.

Today’s advocates of religious toleration, historically informed interpreters of Scripture and open-minded engagement with the full range of contemporary ideas will naturally feel a link to these earlier thinkers.

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Still, these six individuals make a less-than-winning case for the viability of the religious Enlightenment. For one thing, they constructed their theories on what now look like questionable philosophical foundations provided by Descartes, Locke and Christian Wolff.

More seriously, their alliances with state power seem to taint the independence of their thinking. And anyone trying to gauge their religious import may long for more glimpses of inspiration in their spiritual and personal lives behind Dr. Sorkin’s exhaustive account of their ideas.

Most of their stories end sadly, as new generations push aside the pioneers of the religious Enlightenment. The final and extreme case was Lamourette, who tried to slow the French Revolution he had promoted. In 1794, he was guillotined.

The French Revolution and its Napoleonic aftermath not only destroyed the religious Enlightenment in practice; it also created, as Dr. Sorkin notes, a “religious-secular dichotomy” that condemned this side of the Enlightenment to historical obscurity.

Rescuing it from that obscurity, he insists, is of much more than academic interest.

“The twenty-first century has begun with seemingly unbridgeable chasms between secularism and believers,” Dr. Sorkin writes. “One step in averting such a parlous situation is to recover the notion of an Enlightenment spectrum that, by including the religious Enlightenment, complicates our understanding of belief’s critical and abiding role in modern culture.”