Christianity emerged from a fringe movement led by Jesus and his apostles in a tumultuous world characterized by the pluralistic Greco Roman culture and the monotheistic faith of Judaism. In this light, early Christians were greatly marginalized and castigated as the outcasts or outlaws. The Roman emperors and society were no friend of Christians, until Constantine in early 4th century. Social mandate of the gospel was not something in the mind of every Christian then.
The cultural or social mandate (gospel is meant also to transform culture and society, not just for individual salvation) debate dates back to the early church fathers in the second to third centuries. Some argued that Christians were to have nothing to do with the pagan culture. Thus we have the famous line of Tertullian of Carthage: What indeed has Athens to do with Jerusalem? (Implied answer: nothing!) Others (such as Clement of Alexandria and Origen) studied carefully and taught Christians the Greek philosophy and developed informed strategies for Christian apologetics in the pagan society.
The social mandate took on greater urgency, now that the entire Roman empire was Christianized after Constantine. But the Church got its hands dirty and feet stuck deep in the muddy water of power struggle with emperors and local lords and in behavior mortification and controls in the wider society. The Church tried to reform the society through the church institution and sacred sacraments (Baptism, Eucharist, penance, etc) with actionable threats of church disciplines (from denial of sacrament to excommunication, interdict and inquisition). But the City of God did not seem to be an earthly reality, at least not to St. Augustine of Hippo.
Then came the pre-reformation pioneers and reformers. They stood up against the church corruption in doctrine and faith practice. By taking away the corrupted power of institutional church and placing the salvation to each individual persons, the reformers championed a different style of social transformation. The reformers certainly had a tremendous social impact that we still felt today in all denominations of protestanism.
Fast forward our time, we had liberalism in the last two to three centuries. Part of the liberal theology's emphasis was the works of faith and social involvement by Christians. Fundamentalism was a radical counterrevolution to the liberalism movement. They took both the biblical faith and the social issues seriously by taking a highly antagonistic and combative position to every ill of society. Evangelicalism is somewhere in the middle. The radical movements also begot its own less extreme offsprings. Slanted to the liberal side are Neoorthodoxy and liberation theology. Toward the conservation side is neoevangelism.
Personally, I take the cultural mandate as a corollary of the gospel. God seems to save one people at a time, even though occasionally in mission history also through a whole people group movement (but first through one or few individuals). God is more interested in winning a faith community of new humanity, the bride for his son Jesus Christ. Jesus taught in the parable of Kingdom of God that the wheat and tare will grow together until the harvest in the end time. The society will somehow be impacted by the presence and witness of Christians. We Christians are the light of the world. A community of believers is like a city on the hill. It cannot be hidden. In the dark hours of our society, it is the community of faith that shines and gives people hope and light. I would call this approach the Jesus approach, or apostolic approach. All later movements are a revision and partial correction.
