Late medieval and early modern Christianity; the English and continental reformations of the sixteenth century; Lollardy/Wycliffism; heresy and orthodoxy; contemporary American Roman Catholicism; religious affiliation and disaffiliation; sexual diversity and contemporary Christian thought and practice; religion and law.
Hornbeck’s scholarly work focuses on the interplay between the shifting categories of “heresy” and “orthodoxy” in medieval and early modern Christianity; on affiliation, identity, and on issues of marginalization in contemporary Roman Catholicism; and on the contested relationship between religion and law in the U.S.
Much of his early scholarship concerned the “Lollard” or “Wycliffite” movement, which represented the most serious challenge to the authority of the church in late medieval England. In his first book, What Is a Lollard? (Oxford University Press, 2010), Hornbeck argued that traditional historiography, which has viewed lollardy as an organized movement of opposition, neglects important variations among communities of local dissenters.
Hornbeck has also applied his long-standing interests in the categories of heresy and dissent to the area of marginalized practices and identities in contemporary American Roman Catholicism. In this area, he has studied "deconversion" among Roman Catholics (receiving a major grant from the Louisville Institute); described the experience of lesbian, gay, bisexual, and transgender persons in and around the Catholic Church; and commented extensively on Catholic matters in the media.
Returning to the late medieval and early modern periods that are his intellectual home, Hornbeck’s most recent book was Remembering Wolsey: A History of Representations and Commemorations (Fordham University Press, 2019), in which he surveyed portrayals of the English cardinal Thomas Wolsey, who served as lord chancellor and archbishop of York under Henry VIII, in historical writing, works of literature and drama, film, and art.
Hornbeck is presently pursuing various strands of research concerning the relationship between religion and law in the contemporary U.S., including an article on the legal implications of the sexual abuse crisis in the Roman Catholic Church and a larger project on the legal and theological arguments about religious exemptions from generally applicable laws.