The scope of mission in Matt 28:18-20 encompasses the whole of life, including preaching the gospel to every person in all nations upon earth. It is not limited to any race. The church is not to be racial, but one family of all nations, tongues and races. In all nations the gospel is the same one gospel, unchanged by local conditions.
The scope includes teaching people everything that Jesus handed to us through His first apostles. The message is conservative, not changing with generation or culture. We are to teach faithfully what was handed to us. We have no say in what the message is, but as faithful ambassadors, we are to teach what Jesus taught. We do not add to it, nor take away from it: we must continue in the Apostle’s doctrine (Acts 2:42).
This means that mission is teaching the whole counsel of God. It is not specialising in a certain message, such as healing, or prosperity, or kingdom. He did not call us to be “specialists” in the sense of giving people only a part of the message. He called us to be faithful to His whole counsel (Acts 20:27).
“Make disciples of all nations” does not mean of the political nation, but make disciples in all nations. It is the disciples who change the nation by their renewed lives. We are salt, light and leaven in society, bringing godly change at all levels. This is not done by means of churches adopting a “social gospel”, but by preaching the true gospel of Jesus Christ. God then transforms people’s hearts and they impact society.
We can see in history that if believers do not impact society, but hide their light under a bushel, then society will impinge upon the church and eventually overshadow it. It will be trodden under foot by men, governments, laws and armies. Society is not neutral. It is opposed to God unless the people in it are renewed by faith.
This means that Christians should influence business, government, media, education and arts. This does not mean that we should use these fields just to make money. It means Christians bring God’s values, principles and truth into these fields, for the good of the people in society. We are the leaven.
This is one way in which God brings His general grace to the nation for the benefit of all. It allows us to hand on a better society to the next generation. This does not make people in society Christians, but it does mean that all men benefit from the Christian gospel.
Mission includes going into every sphere of human life and preaching Christ and the values of the kingdom of God. We go into all the world (kosmos), every part of man’s life and preach Christ to the people there (Mark 16:15).