God’s mission is a function of his original purpose to form a people for himself. That’s what Israel was to have been: “a kingdom of priests and a holy nation” (Ex. 19:6). The eternal God freely chose to share his life with creatures that he made in his image. This is the original mystery of God’s grace. God ultimately accomplished his mission through the work of his Son and Spirit. It is through Jesus’ death and resurrection and ascension and gift of the Spirit that the church – the society of Jesus – becomes “a royal priesthood, a holy nation, a people for his own possession” (1 Pet. 2:9).
What is needed at the church level is formation. Each member of the church has to be formed to be a member of this holy nation. Each of us has to become a citizen of the gospel, so that we can live a life worthy of our high and holy calling: to be God’s special representatives on earth, ambassadors of Jesus Christ. The church’s mission follows from Jesus’ Great Commission to make disciples. That involves teaching doctrine and spiritual formation. That’s the church’s mission, and that’s the way to shape the culture of a holy nation.