The Crosby-Schoyen Codex, believed to be Christianity's oldest religious book, is set to be auctioned on June 11, according to Christie's.

This codex, part of the Bodmer Papyri collection discovered in the 1950s, was written in Coptic script on papyrus in Egypt between A.D. 250 and 350. It is among the earliest known books and could fetch up to $3.8 million.

Created in one of the first Christian monasteries, the liturgical book includes the complete texts of two Biblical books. Eugenio Donadoni, a senior specialist for books and manuscripts at Christie's, emphasized its monumental importance as a testament to the early spread of Christianity around the Mediterranean. "The earliest monks in Upper Egypt used this book to celebrate Easter, a few centuries after Christ and only a century or so after the last Gospel was written," Donadoni noted.

The Bodmer Papyri collection, to which the codex belongs, comprises various texts, including Christian writings, Biblical excerpts and pagan literature.

This particular manuscript features the first complete epistle of Peter, the Book of Jonah, and an Easter homily. Spanning 104 pages, or 52 leaves, the codex was written by a single scribe during the dawn of Christianity and took around 40 years to complete. Its exceptional preservation is credited to Egypt's dry climate, according to Donadoni.

Initially acquired by the University of Mississippi, the codex remained there until 1981 before changing hands multiple times. Norwegian manuscript collector Dr. Martin Schoyen purchased it in 1988 and is now auctioning it alongside other items from his vast collection, one of the world's largest manuscript archives.