Involved with avant-garde movements such as futurism and post-decadentism, he moved from one political and philosophical position to another, always dissatisfied and uneasy: he converted from anti-clericalism and atheism to Catholicism, and went from convinced interventionism – before 1915 – to an aversion to war.

Working in Florence, he actively participated in foreign literary philosophical and political movements such as the French intuitionism of Bergson and the Anglo-American pragmatism of Peirce and James.

Papini's literary success began with Il crepuscolo dei filosofi ("The Twilight of the Philosophers"), published in 1906, and his 1913 publication of his autobiographical novel Un uomo finito ("A finished man").

Born in Florence as the son of a modest furniture retailer (and former member of Giuseppe Garibaldi's Redshirts) from Borgo degli Albizi, Papini was baptized in secret by his mother to avoid the aggressive anti-clericalism of his father.

He felt a strong aversion to all beliefs, to all churches, as well as to any form of servitude (which he saw as connected to religion); he became enchanted with the idea of writing an encyclopedia wherein all cultures would be summarized.

He would later join the staff of Il Regno,[7] a nationalist publication directed by Enrico Corradini, who formed the Associazione Nazionalistica Italiana, to support his country colonial expansionism.

In 1921, Papini announced his newly found Roman Catholicism,[16][17] publishing his Storia di Cristo ("The Story of Christ"), a book which has been translated into twenty-three languages and has had worldwide success.

In 1940 Papini's Storia della Letteratura Italiana was published in Nazi Germany with the title Eternal Italy: The Great in its Empire of Letters (in German: Ewiges Italien – Die Großen im Reich seiner Dichtung).

[25] According to art historian Richard Dorment,[26][27][28] Francisco Franco's regime and NATO used Papini's series of imaginary interviews in the 1951 novel Il libro nero as propaganda against Pablo Picasso,[29] to dramatically undercut his pro-Communist image.

[30] He was admired by Bruno de Finetti, founder of a subjective theory of probability, and Jorge Luis Borges, who remarked that Papini had been "unjustly forgotten" and included some of his stories in the Library of Babel.