This work explores two influential religions that might seem to have little in common: Twelver Shi'i Islam and Roman Catholicism. With the worldwide rise of religious fundamentalism, it is imperative that religious movements such as Christianity and Islam begin working harder to understand one another's history and beliefs. Myths and misunderstandings continue to prevail, and observers tend to focus on the differences between the two faith systems. Without denying these differences, the authors of this book reveal a number of interesting linkages between Roman Catholicism and Twelver Shi'ism. They compare the histories of the two faiths, consider parallels between important figures in each, and highlight the doctrinal, structural, and sociopolitical similarities they share. The book helps explain the essence of both traditions while enriching our understanding of each. There are an estimated 140 million Twelver Shi'is in the world today. The highest percentages live in Persian Gulf countries, including Iran and Iraq, and in Azerbaijan, Lebanon and Afghanistan. Sizable numbers also inhabit Pakistan, India and Turkey. The largest Christian denomination, Roman Catholicism is present across the globe, though its population of more than one billion is concentrated in North and South America and Europe.