This paper attempts to prove that social capital as social virtues can be interpreted as the value of the kingdom of God, that is, the publicity of the Gospel, which is formed in the process of socialization and culturalization of the Gospel with transformative power at the social level beyond the personal level through work ethics and labor ethics. Therefore, it can be said still insufficient knowledge of human understanding to rely only on the realm of humanities and social science to establish humanity for the restoration of humanness and to identify social capital for social development and integration. Until now, in the study of social capital, the spiritual realm and the role of Christianity, which occupies the most important part in this realm, have been neglected. Therefore, Christian theology can contribute to promoting interest in and research on social capital by meeting the need to bridge the gap between general studies and theology through interdisciplinary research along with the fields of social science. In the meantime, research on social capital has mostly focused on the concept and measurement of social capital and the impact of social capital on society and economy. However, although the concept of social capital itself is multifaceted and related studies are relatively diverse, relatively little is known about the factors that form social capital. Beginning with Robert D. Putnam's research on social networks and Francis Fukuyama's research on trust, research on the factors that form social capital has only been conducted relatively recently. This study also tried to investigate how the spiritual culture of Protestantism has formed the social capital of trust and cooperation through the publicity of the Gospel in these insufficient areas. Moral trust, especially emphasized as social capital, can only be explained as a universal perspective on humanity regarding the image of God. It can be said that this is different from the strategic trust and individual trust often discussed in social capital. According to Francis Fukuyama, the social capital of trust is created when a community shares an systemic moral value structure that pursues a life of normal fairness and common sense. Since this is shared with the Protestant ethics emphasized by Max Weber, it can be asserted that this social capital of trust is based on the ethos of Protestantism as a Christian spiritual culture, that is, the norms of the kingdom of God. In order to understand the social capital formed by Christian humanness, we must understand the biblical truths that constitute humanity. Therefore, in order for the modern society to properly understand the 21st century Protestantism, it is necessary to recognize that the knowledge of God is urgent for modern people. This paper emphasizes the argument that the mission for this is given to the church and the theological community.