After just two days and four secret ballots in the Sistine Chapel, the College of Cardinals elevated Chicago-born Robert Francis Prevost to the See of Peter as Pope Leo XIV—an outcome that underscores the doctrinal rifts at the heart of Christendom and the enduring reasons for our divide. Although Catholics and Protestants often use similar words and phrases, the meanings they attach to those terms are profoundly different. Here are ten doctrinal fault lines that explain why true unity remains out of reach: while we can—and should—show mutual respect, we cannot pretend these convictions don’t exist. It’s the perfect moment...