Filial piety is one of the central issues of Vietnamese culture. It is not only a matter of social morality or human outlook but also has a close relationship with faith - belief and religion of most Vietnamese people. For the Vietnamese, filial piety is an extremely important moral value and a basic - most important standard of human-to-human relationships. The C&MA Evangelical denomination has existed in Vietnam for more than 100 years and although it has affirmed its position with practical contributions, it still encounters prejudice about a religion that teaches people “to deny their roots", "to abandon their grandparents", and “not to be filial to their ancestors", which is contrary to Vietnamese cultural tradition. The research shows the concept of filial piety in the human outlook of the C&MA Evangelical believers from the perspective of the classical analysis of religion. In addition, the author also contributes to clarifying the causes of the C&MA Evangelical Church's failure to practice ancestor worship and analyzing research hypotheses about the relationship between Evangelicalism and Vietnamese culture in the "filial piety" through doctrines, thereby pointing out the most common reasons to answer the question why the filial spirit of the C&MA Evangelical denomination in Vietnam still encounters cultural barriers in the development process.