While still a young man he was compelled to debate in public, on original sin and redemption, with Cardinal Pedro de Luna (later Antipope Benedict XIII).

The disputation took place in Pamplona on December 26, 1375, in the presence of bishops and theologians (see his Eben Boḥan; an extract, entitled "Wikkuaḥ" and in manuscript form, is in the Bibliothèque Nationale, Paris, No.

As a model and guide for this work, which consists of fourteen chapters, or "gates," and is written in the form of a dialogue, he took the polemical Sefer Milḥamot Adonai of Jacob ben Reuben, falsely attributed to David Ḳimḥi.

In the fifteenth chapter, which Ibn Shaprut added later, he criticizes a work written by Alfonso de Valladolid against Jacob ben Reuben.

As part of The Touchstone in order to assist the Jews in defense against conversion and polemical writings, Ibn Shaprut edited or translated portions of the Four Gospels into Hebrew, accompanying them with pointed observations; answers to the latter, written by a neophyte named Jona, also exist in manuscript.