This thesis discusses the landscape of religious institutions and practices in the Gia Định region of South Vietnam under Gia Long’s reign. First of all, I will introduce the Vietnamese term of phong tục to illustrate why religious practices were secular rather than sacred to Vietnamese people. Then I will discuss the court policies towards religious practices during Nguyễn Ánh’s campaign against Tây Sơn rebels during the 1790s to 1802 and its transition after 1802. This not only illustrates how the court utilized the construction of religious institutions to promote political agendas but also demonstrates how a basic Confucian ideology of morality and rites permeated through different levels of Vietnamese society. In the last section, I will argue that under the surface of Confucian influence, both court policies and local religious practices showed trends of religious syncretism.