In contrast to the cognitively optimal religion in the previous chapter, this chapter examines the theological system in the book of Deuteronomy as an example of cognitively costly religion. Deuteronomic theology is characterized as a highly literate, reflective, and abstract tradition with complex doctrines such as the so-called Name Theology of divine presence, cult centralization, and aniconism or iconoclasm, all of which radically depart from prevailing cultural expectations. Each of these key tenets of the Deuteronomic theology is analyzed within the framework of intuitive and reflective cognition and cognitively costly religion. Moreover, understanding Deuteronomy as a type of costly religion helps to account for the book’s unique emphasis on teaching, repetition, and instruction. Deuteronomic theology is best understood as a form of what Harvey Whitehouse calls the doctrinal mode of religiosity.