We explore the possibility that a priori philosophical commitments continue to result in a narrowing of inquiry in moral psychology and education where theistic worldviews are concerned. Drawing from the theories of Edward L. Thorndike and John Dewey, we examine naturalistic philosophical commitments that influenced the study of moral psychology and moral education in the USA. We then address the question of whether these foundational naturalistic commitments can be rendered as compatible with theistic commitments, using both modernist and postmodern philosophical approaches that might be viewed as attempts at compatibility. Arguing that these attempts at compatibility fail, we draw from contemporary approaches to moral psychology and education in order to illustrate how naturalistic commitments might prevent these approaches from adequately addressing theistic understandings and experiences of morality.