The paper demonstrates the utility of digital models and simulations in the study of light in sacred architecture. Specifically, it applied this method and analyses on Frank Lloyd Wright’s treatment of light in Unity Temple, Oak Park, Illinois (1905). The findings of the light simulations augmented the observation and qualitative analyses of Wright’s lighting design and show that his treatment of light fulfilled the accentuated, architectural, and celebration lighting recommendations of IES, while the task lighting of reading was partially fulfilled. Still, Wright’s original design provided the dramatic effect of light and shadows and enhanced the spiritual experience in the Temple.