The eruption of civil wars in Muslim-majority countries and a spate of acts of terrorism by Muslims in Western cities has brought renewed urgency to an age old question: is Islam more prone to violence than other religions? Specifically, does the Quran-which Muslims believe to be the actual word of God-sanction and encourage bloodshed, and does it do so more than do other holy texts? We answer this question using a supervised machine learning algorithm which allows us to score the violence propensity of each verse of the Qur'an, the Old Testament, and the New Testament and classify them into one of three categories: collective, interpersonal and self-directed violence. We find that the Quran and the Bible, taken as a whole, contain a roughly equal proportion of verses that reference interpersonal and collective violence. When we explore the promotion of each type of violence, we find that the Bible has a significantly higher proportion of verses which promote interpersonal violence while the Quran has a significantly higher proportion of verses which promote collective violence. We stress that these findings do not necessarily imply that the language of the Quran is a sufficient or even necessary condition to explain the greater current collective Muslim violence. First, the Christian world has arguably seen much more violence than the Muslin world. Second, alternative or complementary factors, such as an authoritarian regime or a weak state, may be major promoters of violence. Third, even if holy texts do help to enable violence, just a few passages might be sufficient. Such complementary and alternative explanations, not explored here, should be the subject of future work.