This chapter examines the influence of religion on US foreign policy. It first considers how religion affected American policy during the Cold War, from the time of Harry S. Truman to George H. W. Bush, before discussing the bilateral relationship between Israel and the United States. It then looks at the rise of the American Israel Public Affairs Committee (AIPAC), a US-based interest group, and how its work has been complemented by conservative evangelicals and fundamentalists who ascribe to Christian Zionism. It also explores the ways in which religion has intersected with the global war on terror and US foreign policy, how the US resorted to faith-based diplomacy, the issue of religious freedom, and George W. Bush’s Emergency Plan for AIDS Relief (PEPFAR) in Africa. The chapter concludes with an analysis of the Office of Religion and Global Affairs (ORGA), created by Barack Obama.