From Calvinist to Catholic: Letters from Peter Kreeft’s Conversion to Rome (Ignatius Press, 2025)
Peter Kreeft is unarguably one of the most important Catholic voices of the last fifty years or so. His recent autobiography, From Calvinist to Catholic: Letters from Peter Kreeft’s Conversion to Rome, gives meaningful insight into this Catholic leader’s life. For those Protestants interested in the story of how a boy raised in the Reformed Protestant world could eventually convert to Rome, the book is quite helpful.
Kreeft was born in Peterson, New Jersey, and would eventually be educated at Calvin College (B.A.), Fordham University (M.A. and Ph.D., though he started his graduate work at Yale), and he returned to Yale for postdoctoral studies). He has taught philosophy at Boston College since 1965).
Kreeft began questioning his Protestant roots and upbringing as a teenager, but things ramped up at Calvin College, especially as young Kreeft began to have questions about the history of the church. He is candid, and writes: “My heart started moving down the road to Rome earlier than my head.” (p. 67) He also writes: “It began with Saint Patrick’s Cathedral and with my reading of Saint John of the Cross as a teenager, not understanding what he was writing about but ‘just knowing’ that it was true, and real, and massive, like a mountain.” (67)
Kreeft is fond of lists. For example: “Seven Most Important Anti-Catholic Objections.”
(The most important: “Catholics did not know the single most important truth about Christianity, namely, the answer to the question ‘What must I do to be saved?’ (Acts 16:30).” (p. 75)
Kreeft discusses key steps along the way. The first, not surprising, is his encounter with Thomas Aquinas (via his Calvin professor Harry Jellema), especially Thomas’ notion of “grace perfecting nature. (87)
Another key list: Ten theological axioms or principles. We note the first two (1) The relationship between Christ and the church; (2) nature and grace. Concerning the first principle, Christ and the church, Kreeft states that his growing/incipient Catholicism “forced me to raise my view of the Church up farther, closer to Christ Himself, than my Protestantism allowed me to do.” (92) Concerning the second, nature and grace, Kreeft writes: And the Catholic principle that I saw consistently followed by the Church, but not so much by Reformation Protestants, was the principle that grace perfects nature rather than rivaling it. I saw this principle everywhere in Catholicism but frequently forgotten or violated in Protestantism.” (p. 92)
As the book proceeds, Kreeft focuses on especially key issues:
· A chapter on the church (chapter 13)
· A chapter on nature and grace (chapter 14)
· A chapter criticizing sola scriptura, sola fide, and sola gratia (chapter 15)
· A chapter criticizing the five points of Calvinism (chapter 16)
· A chapter on sacraments, sacramentalism, and the eucharist (chapter 17)
· A chapter on Mary (chapter 18)
· A chapter on the communion of saints—i.e., why it is proper to pray to the saints (chapter 19)
· A chapter on Thomas Aquinas (chapter 20)
· Two chapters on Kreeft’s road to Rome as it developed at Yale (chapters 21 and 22)
So, through chapter 22 essentially recounts Kreeft’s conversion to Roman Catholicism. Chapters 23 through 23 then recount his post-conversion life, moving to the present day.
In many ways, Kreeft’s road to Rome is not unique—the various twists and turns will be very familiar to readers who have either travelled this road themselves, or who have read of other such journeys. As Kreeft recounts, he was puzzled by church history? Where did the church come from? What is its authority? Kreeft came to affirm that Christ established the Church (as Protestants would likewise affirm). But this notion gets developed and worked out in Kreeft’s journey, such that he virtually must convert to Rome. As Kreeft writes:
Is there an identity and a seamless web of continuity between the thing Christ founded in the New Testament and called His “Church”, on the one hand, and the visible institution that exists today and calls herself the one true Church, the one holy Catholic (universal) and Apostolic Church, which is the only Church that has those four “marks of the true Church” that are thus listed in the Nicene Creed? (94)
Similarly, Kreeft became attracted to the Thomist maxim, “grace perfects nature.” (pp. 105ff.) But there is not wrestling (as far as I can see in this work) with Protestant versions of this maxim, or Protestant hesitancy with this maxim.
Let me offer a few general reflections on Kreeft’s road to Rome, as recounted in From Calvinist to Catholic.
1. First, while Kreeft is a very smart and accomplished man, I was struck by how basic and fundamental (and fairly unsophisticated) the reasons for his conversion were. If one is wanting a thoughtful and thorough and penetrating engagement with the best of Protestant thought on the points of tension between Protestantism and Rome, this book is not the one for you.
2. Kreeft’s journey to Rome was in one sense a slow and an ongoing process . . . and it began with the heart. Kreeft is quite forthright that there was a heart-filled draw to Rome at first, which was followed by an intellectual move.
3. In another sense, it seems that Kreeft’s journey to Rome was rather quick. That is, he was “converted” before he was fully converted. That is, as Kreeft recounts his journey to Rome, it almost seems that he was already there before he was really there.
4. Second, as I read Kreeft, I was not sure that he had ever immersed himself in the history, glory, and strength of the Reformed tradition. That is, it seems that Kreeft’s summaries of Reformed thought/theology were fairly surface and at times something of a straw man.
Here are a few examples:
· Calvin supposedly affirmed divine sovereignty but denied free will (is that the heart of
Calvin’s position?)
· Is Luther simply a “nominalist,” and that settles it?
· Was there really no strong affirmation of “works” in the Christian life for the
Reformers—that is: Kreeft never mentions Calvin’s “two-fold grace,” where Calvin can say that God never justifies someone without sanctifying them (and that sanctification includes the “necessity” of works in the life of a true believer).
I was somewhat sad reading the book. By the end of the read there had been little meaningful engagement with the best of Protestant thought and doctrinal construal. I choose to believe that Kreeft must know something of the best of Protestant thought. But one would not know this from reading this book.
5. I was struck again and again, that Kreeft certainly sees Rome as a system, and he is not the least bit shy are hesitant to affirm this: the Christ-church relationship, linking to apostolic succession, linking to Mary, linking to the efficacy of the sacramental system, etc.
From Calvinist to Catholic is nonetheless worth the reader’s time. While it does not really get to the nub of the disagreements between Rome and Protestantism, it most certainly gives insight into one of the finest Catholic thinkers in my lifetime, and one whom I have enjoyed reading for many years.
Bradley Green is a Reformanda Initiative Fellow and Professor of Philosophy and Christian Theology at The Southern Baptist Theological Seminnary. Before joining the Southern faculty full-time in 2026, he served as a Visiting Professor there and as Professor of Theological Studies at Union University (Jackson, TN) for 28 years. While in Jackson, Brad and his wife Dianne helped found Augustine School, a Christian liberal arts school. Green has also served as Writer-In-Residence at Tyndale House, Cambridge. He and his wife have 3 children.
