Oren Jacoby's documentary Constantine's Sword is about three things: first, the life story of a former Catholic priest, James P. Carroll; second, the facts and myths of Christianity's rise from obscurity to a global institution; and third, the history of the European persecution of the Jews. The documentary begins with Carroll, now a journalist, investigating a story about anti-Semitism at an air-force academy in Colorado Springs that's increasingly dominated by Christian fundamentalists. Carroll starts to believe that the source of the anti-Semitism at the air-force academy and nearby megachurches—one of which is run by none other than Ted Haggard—is not exceptional but part of a tradition that goes all the way back to Constantine, the Roman emperor who converted to Christianity in the fourth century and forever changed the course of Western civilization.

According to Carroll's investigation and research, which is also contained in his 750-page book of the same name, what Emperor Constantine brought to his new religion was not peace but war—war against those who did not believe that Christ died for their sins and, eventually, war against those accused of killing Jesus: the Jews. The Crusades, as Carroll points out later in the documentary, were not only against Islamic Arabs but Jews as well. And this early persecution of the Jews was a part of a path that led all the way to the ovens of Auschwitz.

Despite its wealth of historical information and revelations, the documentary feels a little flat, and several of its crucial moments and insights would have benefited immensely from a little poetry and passion. We must not be mild about this history of violence and madness. We must never forget that Christianity is a huge body that's covered in blood.