The Rev. George Leslie Mackay arrived to Tamsui, Taiwan in 1872. When he began his mission work in Taiwan, there were three religious traditions in Taiwan: Confucianism, Buddhism, and Taoism. Throughout his life, Mackay did not discuss in detail the relationship between Christianity and other religions. Neither did he analyze Christian attitudes regarding other religions. Chapter 13 of From Far Formosa is the most complete account in Chinese that we have thus far regarding these two subjects. Some information can also be found in Mackay’s own diary wherein he writes about his mission work. In this essay I will try to elaborate on the relationship between Mackay and Taiwanese religions. Despite limited information available to me, I will endeavor to expound on the relationship between Mackay and Taiwanese religions using Mackay’s 19th century theological background as my point of reference. It is my conclusion that Mackay used eschatology to relate to other religions while he did mission work. His beliefs were similar to perspectives on “Justice, Courtesy, and Love” prevalent in the discipline of mission theology in the 19th century. It is through mission work that Mackay actualized his theology in Taiwan and discovered in the process how to relate to other religions.