Brett Salkeld has written an accessible book on a difficult subject: the Catholic doctrine of transubstantiation. Salkeld writes with a light touch, seeking to build ecumenical bridges rather than knock down opponents. He’s clear about his convictions. Rather than being an insurmountable stumbling block, Thomas Aquinas’s classic formulation of transubstantiation provides a way through the theological weeds. As Salkeld points out, while transubstantiation may be regarded as a lynchpin of Catholic/Protestant disagreement, in fact it’s “a word that almost no one, Catholic or Protestant, actually understands.” Acceptance or rejection of the word has moved beyond theological utility to become an “identity marker.” Salkeld seeks to recover an authentic understanding of transubstantiation as a way to maintain the two great strands of Eucharistic reflection: the symbolist and the realist, represented (historically if not in actual fact) by Augustine and Ambrose.

There are challenges. Transubstantiation draws on Aristotle’s antique worldview, which leaves it open to charges of both being pagan and outdated. However Sankeld demonstrates that Thomas did not merely use, but also transformed Aristotle, in what he calls “Aquinas’s re-inscription of Aristotle’s physics.” So too, transubstantiation seems unnecessarily speculative. Why not follow Luther and “cling simply to the words of Christ?” Because, writes Salkeld, “in order to avoid devolving into fideism or skepticism, faith must seek understanding.” Perhaps the greatest challenge to Salkeld’s project is the confounding difficulty of understanding exactly what Thomas was saying with transubstantiation, with its specialist vocabulary of substance and accidents, local vs. nonlocal vs. repletive vs. circumscriptive vs. definitive presence. Take this line from the Summa in which Thomas describes how Christ is present “in the way that substance is under dimensions, and not in any dimensive way, i.e., not in the way that the dimensive quantity of a body is under the dimensive quantity of the place that contains the body.” Not for nothing Luther punched at the Catholic status quo in his Babylonian Captivity of the Church by claiming that no layman could hope to understand Thomas’s “fine-spun theology.” At least for a newbie reader of Thomas like me, Salkeld’s words describing pre-Thomistic eucharistic theology ring a little true of transubstantiation as well: “the resulting [theological] machinery ends up with so many tiny moving parts that it breaks very easily and requires a high level of expertise to repair.”

The book shines as a comparative work, taking a deep dive into Luther and Calvin as representative strains of Protestant eucharistic theology. Luther tilted toward the realist side and in so doing “lost his grip on the sacramental nature of the Eucharist when he ignored the significatory value of the bread and the wine.” Calvin, though often inaccurately lumped with Zwingli, invokes the Holy Spirit to describe how Christ is present both in heaven and in the elements. But Calvin ultimately fails to distinguish if or how “the Sacrament actually offers us something or only confirms that we possess it already.” For Salkeld, transubstantiation, with its careful distinguishment between the real substance of Christ present and the symbolic power of the bread and wine, is the cure for what ails Protestant eucharistic theology.

With the earnest ambition of a true ecumenist, Salkeld shares his wish list at the end of the book. “Transubstantiation need not be an ecumenical stumbling block,” concludes Salkeld. Instead, he holds three noble hopes: that Christians will realize that ecumenical agreements on the Eucharist are “not a fudge” but stand on authentic shared convictions; that “ecumenists may be emboldened to treat the question of transubstantiation head-on;” and that “clarity and consensus” on transubstantiation can “spur ecumenical hope.”

Whether Salkeld’s ecumenical hope can be realized or not, this book makes clear that transubstantiation deserves more than to be just waved away by skeptical Protestants and Evangelicals. As Salkeld demonstrates, transubstantiation is a compelling and authentic expression of fides quaerens intellectum.