There are books one reads for answers—and books one reads to learn how arguments ought to be made. "When Did Jesus Become God?" belongs firmly to the latter category.
While marketed as a debate on early Christology—specifically, whether Jesus was understood as divine from the earliest strata of Christianity or gradually exalted in later tradition—the true intellectual substance of this volume lies not in its conclusions, but in its methodology. For me, the most enduring and quietly luminous component of the book is not the exchange between Bart Ehrman and Michael Bird, but Robert B. Stewart’s introductory essay: “Instructions for Assessing Historical Arguments." It is here that the book accomplishes something rare and commendable—it equips the reader not merely with positions, but with the tools required to judge between them.
Stewart’s essay offers a lucid and disciplined breakdown of historical reasoning into its working parts: defeaters, abductive reasoning, the burden of proof, criteria of authenticity, and cumulative-case arguments. These concepts—standard fare for trained historians, philosophers, and textual critics—are too often glossed over in popular religion-writing. Stewart does not merely list them; he teaches them. He explains how arguments may fail not only because they are false, but because they are underdetermined, poorly constrained by evidence, or blind to rival explanations. He introduces abductive reasoning not as conjecture, but as disciplined inference to the best explanation. He treats “criteria of authenticity” not as magical sieves but as probabilistic tools—fragile, fallible, and easily misused.
In short, Stewart reminds the reader that historical thinking is not the accumulation of facts, but the art of weighing explanations under conditions of scarcity, bias, and distance. And that, to my mind, is the real book.
The remainder—a transcribed debate between Ehrman and Bird—reads like what it is: a live intellectual exchange frozen in print. Both scholars are accomplished; both are working within serious frameworks of historical inquiry. Ehrman presses his familiar thesis of early “exaltation Christology”—that Jesus was not originally regarded as divine but was increasingly elevated in theological status over time. Bird, by contrast, defends an early “high Christology,” arguing that reverence of Jesus as divine appears shockingly early within Jewish-Christian communities.
But if Stewart offers architecture, the debate offers atmosphere. It captures something oddly honest about live debates: not the triumph of reason but the collision of frameworks. Arguments are repeated rather than refined. Evidentiary challenges are parried rather than settled. Nuance collapses under the pressure of time constraints and rhetoric. One does not get synthesis; one gets survival. The experience is less like witnessing dialectic and more like observing tectonic plates grinding past one another—each massive, each unyielding. This is not a fault of either scholar; it is just, unfortunately, the nature of adversarial format itself.
So while the debate may interest devoted students of Christology, I found it less illuminating than exhausting—an exercise in intellectual endurance rather than historical clarity. Much of it is, in any case, already accessible online in audio and video form.
Paradoxically, then, the book’s deepest value lies not in its primary marketed conflict, but in its preface. Therefore, if you approach it with hopes of learning how historical claims are built, contested, weakened, and defended—and how belief is justified under uncertainty—then Stewart’s essay alone earns my recommendation.