Christian history has been full of events to happen in the result of that whether the people called by God have obeyed His Words or listened to other words different from His. In the history of the Old Testament, God gave the covenant through Noah and Abraham (Gen. 8, 12), and let His people know His laws through Moses. God`s people have responsibility and duty not only to preserve but to keep the laws as His divine commandments. In the New Testament, God gives "the Great Commission"(Matt. 28:1820, Acts 1:8; Mk. 16:15) to His people through Jesus Christ in order to fulfill the ultimate purpose. Missions is the work to preach the Gospel of God`s Kingdom by God`s people for nonbelievers. The method and strategy can vary in nature according to the culture, but ultimately the essence of the Gospel should not be distorted. The Bible is the record of God`s redemptive history from Genesis to Revelation. In other words, missions is that the sinners in the world may obtain eternal life through the missionary work(Jn. 3:16; Matt. 28:1820). This is the simple and clear truth not to be negotiated or compromised. Above all, the Gospel urges to repent to God to all people, and it says the Good News to be the grace of forgiveness through the work of Jesus Christ(Lk. 24:4648). Both theologies of the Reformed Life and John Calvin put emphasis on the biblical foundation for missions. The sins of people have even spread in any society regardless of gender, age, occupation or organization. If he or she cannot resolve the problem of sin in essence, s/he cannot achieve peace and justice even in the world. The Gospel is indicating the problem and is providing the simple and joyful message so that the sinners can be God`s people through the forgiveness of sins in Jesus Christ. Calvin constantly says that the core of the gospel is to preach repentance and forgiveness of sins(Lk. 24:47; Acts 5:31). It is that Calvin has the desire of salvation to enter the Kingdom of God as "the goal of faith" (scopus fidei). Accordingly Christian missions must preserve, protect and proclaim the "traditional constants" of the church. At the same time it must set up clearly the "constants" in order to react creatively and boldly in different context in terms of mission theology. Evidently John Calvin and the Reformed Life theology have provided the essence of missionary theology on the basis of biblical authority.