Missions is about the Great Commission. It is about the church obediently and passionately making disciples of the Lord Jesus Christ in all nations by evangelising the lost, baptising converts, and teaching disciples to everything that Jesus has commanded. This is the responsibility of the local church.
Now the eleven disciples went to Galilee, to the mountain to which Jesus had directed them. And when they saw him they worshiped him, but some doubted. And Jesus came and said to them, “All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.”