For Christians living in a culture prone to “canceling” those with unacceptable views, Salt and Light offers a different perspective. This biography of Élisabeth Leseur and her atheist husband, Félix, is a testament to the vocation of marriage and the transformative power of God’s love. But even more importantly, it points each of us to our ability and duty to – in Élisabeth’s own words – “love souls.”

Élisabeth, a devout Catholic, learned of her husband’s atheism on the eve of their wedding in 1889. While she resolved to keep practicing her childhood faith, Félix intended to reason with his new wife with the goal of “liberating” her from Christianity. He succeeded for a time, but Félix underestimated his wife’s intelligence. The owner of an extensive personal library, Élisabeth maintained a rigorous self-education, learning Latin, Russian, and philosophy.

When Félix gave Élisabeth some reading material he thought would dismantle her Christian beliefs for good, his offer had the opposite effect. Élisabeth saw the weaknesses in arguments proposed by authors like Renan and Voltaire, who had led so many Christians to lose their faith. She immersed herself in intellectual and theological works and built up a wealth of counter-arguments in favor of the existence of God.

But Élisabeth kept quiet about these, choosing to write them down in a diary rather than create debate with her husband. She followed this practice her entire life, believing that controversy, especially within a couple, was pointless. Instead, as her faith blossomed Élisabeth chose to let her joy show the interior peace that faith brought her.

The book takes us through Élisabeth and Félix’s marriage and their vibrant life of travel, their conversations with some of Paris’ greatest intellectuals, and their deep love toward one another. Élisabeth’s lifelong illness surely added strain to their marriage. Felix cared for her lovingly, but much of the pain she bore quietly, secretly offering it up to God for the conversion of her husband. After her death at age thirty-four in 1914, he discovered her personal diaries, which ultimately led to his entering into the priesthood.

Élisabeth was willing to listen to the ideas of others even when she did not agree with them. Through patience, tolerance, and an intensive study routine – which Élisabeth deemed crucial to the life of any woman – she was able to participate actively in the intellectual atheist circles she and her husband frequented without compromising her own faith. Instead of confronting those whose way of life differed from her own, Élisabeth took a position of empathy and focused on prayer and her own spiritual formation.

Élisabeth did not see it as her duty to proselytize or convert as many people as possible, but to busy herself with doing good toward what she referred to universally as “souls.” In a letter to her nephew she reminded him that everywhere there are “material or moral miseries to ease, minds to calm, hearts to heal, seeing in all those who you will meet on your way the soul that is in them.” Her acceptance of all people was her ultimate strength.

Well acquainted with the hostility that the mention of God often provoked in her atheist friends, Élisabeth chose instead to let her faith shine through her words and deeds, writing that she would “make loved, through me, Christian truth.” She desperately wanted her husband to return to the faith and resolved to “show him the fruits without the lifeblood, my life without the faith that transforms it, the light that is in me without speaking of the one who brings it to my soul.” Her decision not to talk explicitly of God was not a denial of him, nor what some today would call “lukewarm faith” or “cultural accommodation,” but her own way of gentle evangelization.

She still suffered greatly from this approach. Despite her faithfulness to an interior life of prayer and silent suffering, such a spiritual isolation was almost unbearable to her. Nothing was more painful than withstanding her husband’s mockery and criticism of her faith, and to exercise charity in return. Félix understood this after reading her diaries, and it became one of his greatest regrets. Élisabeth believed that arguments would put a strain on her marriage and insisted that “silence is … conducive to humility.”

While Élisabeth instructs us to stand by our principles, to study our faith in order to defend it, and to show that “one can be both intelligent and Christian,” this masterfully researched account of her life and of Félix’s conversion is proof that nothing is more effective in terms of evangelization than kindness and empathy. Beautifully translated and thought-provoking, this book is not simply the Parisian love story of two people who did not share a faith, but a guide to loving those whose beliefs and ideas differ from our own. It attests to the real pain that can come with being faithful to one’s vocation and to the hope that can be found in trusting God with all things, most especially our loved ones.

Salt and Light is an encouragement for mixed-faith relationships and a reminder of Jesus’s ultimate message: to love one another as he loves us.