This present study explores theology of John Calvin’s social engagement in terms of its social inclusivism. Historically, Calvinism has been known as developed strict reformed tradition which led its relation to the society in dualistic conflict. However, John Calvin’s Geneva Reform clearly showed that his reformation has developed in the idea of mutual relation between the Church and the Society. Calvin underscored the Christian consecration of the Church, and socially practiced the embrace of gospel in order to prevent any form of discrimination and prejudice. Calvin’s inclusive dualism served as an outstanding theological reflection that shows what kind of attitude Calvinism should take toward society. The distinctive of Calvin’s theology has been developed as more contemporary Reformed theology through the works of Abraham Kuyper. In his book “Lectures on Calvinism”(1898), he provided the new value of Calvinism which can be identified as a system of holistic human life. It offered the social inclusion of theology that helps to reorganize historical Calvinism in order to meet the demands of the future era.