Most people know Mary Baker Eddy as the founder of Christian Science, and Victoria Claflin Woodhull as a pioneering suffragist, the first female candidate for the American presidency. But for Cindy Peyser Safronoff, it was looking at the two women’s long debate over the issue of marriage that revealed fascinating differences and similarities.

In “Crossing Swords: Mary Baker Eddy vs. Victoria Claflin Woodhull and the Battle for the Soul of Marriage,’’ Safronoff chronicles the two women’s long-running dispute, played out mostly in editorials and lectures, over whether marriage was a threat to women’s equality and should be abolished (Woodhull’s view) or an opportunity for true partnership (Eddy’s stance). Despite their entrenched opposition on this point, the two had much in common, Safronoff pointed out. Both gained prominence in an era, just after the Civil War, when American cultural, political, and religious life was uniquely poised for change.

When it came to Eddy and Woodhull on marriage, Safronoff said, she felt she “had stumbled on America’s 19th century culture war.’’ She hadn’t planned to write about the topic at all, Safronoff said, adding that she happened upon the book’s subject while doing research. “Most of the juicy stuff came from the footnotes of other people’s biographies,’’ she said. “That was its working title: ‘Footnotes.’ ’’

But these women — both of whose archives now reside in Boston — were anything but incidental, she added. “There’s more to be told,’’ she said. “I’m planning on a sequel.’’

Safronoff will read 7 p.m. Tuesday at Harvard Book Store.

Kate Tuttle, a writer and editor, can be reached at kate.tuttle@gmail.com.