He was the second of six sons of Jean-Baptiste Bloy, a Voltairean freethinker, and Anne-Marie Carreau, a stern disciplinarian and pious Spanish-Catholic daughter of a Napoleonic soldier.

[1] After an agnostic and unhappy youth[2] in which he cultivated an intense hatred for the Catholic Church and its teaching,[1] his father found him a job in Paris, where he went in 1864.

Bloy was a friend of the author Joris-Karl Huysmans, the painter Georges Rouault, the philosophers Jacques and Raïssa Maritain[3] and was instrumental in reconciling these intellectuals with Catholicism.

"[5][6] Bloy's first novel, Le Désespéré, a fierce attack on rationalism and those he believed to be in league with it, made him fall out with the literary community of his time and even many of his old friends.

Soon, Bloy could count such prestigious authors as Émile Zola, Guy de Maupassant, Ernest Renan, and Anatole France as his enemies.

Bloy is also quoted at the beginning of John Irving's A Prayer for Owen Meany, and there are several quotations from his Letters to my Fiancée in Charles Williams's anthology The New Christian Year.

[14] According to the historian John Connelly, Bloy's Le Salut par les Juifs, with its apocalyptically radical interpretation of chapters 9 to 11 of Paul's Letter to the Romans, had a major influence on the Catholic theologians of the Second Vatican Council responsible for section 4 of the council's declaration Nostra aetate (1965), the doctrinal basis for a revolutionary change in the Catholic Church's attitude to Judaism.