In 1807, American readers were titillated by a potboiler entitled “History of the captivity and sufferings of Mrs. Maria Martin.” Its salacious story was summed up by its pithy subtitle: “Who was six years a slave in Algiers, two of which she was confined in a dark and dismal dungeon, loaded with irons for refusing to comply with the brutal request of a Turkish officer.”

We often forget that Americans have been thinking about Islam for centuries. In the republic’s early days, Muslims not only accounted for a large part of the enslaved labor force but also often appeared in stories as fearful figures in far-off places—dark hazards to American virtue. These old images help illuminate today’s American debates about Islam.

In the early republic, popular accounts of “Mohammedanism” were largely limited to tales of the capture and enslavement of Americans in Muslim lands. Narratives like Mrs. Maria Martin’s joined fears of North African pirates with titillating plots of kidnapping. They echoed the era’s best-selling accounts of colonists trapped by American Indians.

As the 19th century progressed, some abolitionists began to argue that Islam had things to teach Christianity. Slavery’s foes called slave owners in Muslim lands more fair than their U.S. counterparts.

In 1810, for instance, the New Hampshire Patriot ran a story called “Mohammedan Forbearance,” depicting a Muslim caliph as a model of faith and morality. Even after a slave spills a dish and scalds him, the caliph treats the slave well and later frees him, quoting the Quran to buttress his mercy. This example, the journal says, “might be usefully imitated by the professors of purer doctrines.” ...