If we look at human nature from the perspective of classical economics, religion and economics do not seem to be directly connected. While religion represents the pursuit of noble values namely truth, beauty, happiness, holiness, and selflessness, doing business is unanimous with the worship of material wealth. However, a closer examination would reveal the interrelations between these two realms. A strong religious belief can actually have significant influence on the way the believers engage in their businesses toward the path of righteousness, and a thriving business could, in turn, enhance the followers’ commitment to the religion. Although the connection between religious belief and economic activities has been discussed in the literature, limited scholarly attention is paid on the phenomenon among the Catholics in Vietnam, a community that has not been examined considerably on areas other than their religious practices or political involvement in the past. Based on an ethnographic study of the Catholics’ economic activities in the Mekong Delta, especially in Cái Mơn Parish in Bến Tre province and the Main Parish in Cần Thơ city, this article argues that religious beliefs could influence and govern the economic behaviour of Catholic followers through the values of honouring God, justice, and charity. These values have inspired the principle of “getting rich righteously” among the Catholics in the Mekong Delta and motivated them to fulfil their civic obligations in society at large. Findings from this study helps shed light on the religious beliefs—economic activities engagement and contribute to the literature on Catholics’ economic activities in Vietnam, an area which remains understudied.