Thomas M. Izbicki, Ph.D. (Cornell University, 1973), is a humanities librarian emeritus at Rutgers University. He is a researcher in the fields of medieval canon law, the history of the papacy, and the history of the Order of Preachers. He has published Protector of the Faith: Cardinal Johannes de Turrecremata and the Defense of the Institutional Church (1981) and The Eucharist in Medieval Canon Law (2015).Jorge Ledo, Ph.D. (University of Aberdeen, 2009), is a ‘Ramón y Cajal’ Researcher at the Universidade da Coruña (Spain). He is an intellectual historian specialized in Renaissance Humanism and in the history of religious minorities and religious dissidence in early-modern Spain. He has published Moria de Erasmo Roterodamo. A Critical Edition of the Early Modern Spanish Translation of Erasmus's Encomium Moriae (2014).

"This edition of the Tractate against the Midianites and Ishmaelites will be immensely useful to scholars of fifteenth-century Iberia, intellectual and religious history, as well as those exploring questions of premodern race and racialization. The format and critical apparatus mean that the text—written by one of the most important Curia theologians of the mid-fifteenth century—could also serve as a good introduction to late medieval Latin and theology for advanced students. Overall, it is a welcome addition to Brill’s Heterodoxia Iberica series." — Bert Carlstrom, Queen Mary University of London"Thanks are due to Thomas Izbicki and Jorge Ledo for making available a very important text in its first English translation, based on three different manuscripts." — Michaela Valente, Sapienza Università di Roma, in Renaissance Quarterly 79.2 (Summer 2026)

• AcknowledgmentsIntroduction: Juan de Torquemada’s Defense of the Conversos1 The Revolt in Toledo, 14492 The Manuscripts, Editions and Translation3 Conspectus siglorumTract against the Midianites and Ishmaelites, Foes and Detractors of the Faithful Who Originated from the Israelite People[Prologue]1 In Which It Is Shown from a Description of the Quality of the Aforesaid Trial That It Is of No Force or Moment2 In Which the Things Cited against Christ’s Faithful Descended from the Israelite People Are Proved to Be Erroneous3 In Which It Is Shown That the Second Foundation Cited by the Foe in Favor of Their Impiety against Those Newly Converted to Christ’s Faith Descended from the Israelite Nation Is Erroneous and Blasphemous4 In Which the Aforesaid Error Is Refuted in a Second Way, with Reasons5 In Which the Aforesaid Error Is Reproved from the Divine Promises Made to the Israelite People6 In Which the Aforesaid Error Is Reproved from the Deeds Done by Christ among the Jewish People7 In Which One Authority Cited in Favor and Proof of Their Aforesaid Errors Is Answered8 In Which the Second Authority Cited on the Part of the Foe Is Answered9 In Which the Third Authority Cited for the Adverse Part Is Answered10 In Which the Fourth Authority Cited for the Adverse Part Is Answered11 In Which the Fifth Passage Cited by the Often-Mentioned Midianites and Ishmaelites in Favor and Support of Their Sacrilegious Presumption Is Answered12 In Which the Principal Conclusion of the Foe Is Shown from the above to Be False and Erroneous13 That the Unbelief of Those from Whom They Descend Must Not Be Imputed to Those Converted to Christ’s Faith from the People of the Jews14 In Which Reasons Are Assigned Why Converts to Christ’s Faith, and Especially Those from the Israelite People, Are Not to Be Despised by the Other Faithful, but Rather Loved and Honored15 In Which the Error and Malice of Those Who Presume to Posit a Difference between Those Converted from the Israelite People and Other Christians Is Confuted16 In Which Those Things Which the Aforesaid Adversaries Cite in Favor of Their Rashness Are AnsweredAppendix: Pope Nicholas V: Humani generis inimicus (Fabriano, 24 September 1449)BibliographyIndex of Scripture ReferencesIndex of Classical and Medieval AuthorsIndex of Scholars Cited