By dying and rising again, Jesus made it possible for sinful human beings to be forgiven and for all things in heaven and on earth to be reconciled to God. Mission which doesn't include this message doesn't really deserve to be called mission, in the first place.
Yes we have to obey Christ's command at the end of Matthew's Gospel, just as we have to obey all his commands. But the Bible's story of mission doesn't start and end there - and nor should ours.
The main way that the Gospel is spreading around the world is through the quiet, but determined witness of Christians whose names we have never heard of (and would struggle to pronounce).
What is the message of the Magi and how do they fit into Matthew's Gospel?
A brilliant quote that answers the why, who, what and (too some extent) where of mission.
The Gospel is inherently counter-cultural. It challenges both the ideological/theological systems of the world as well as those of cultural Christianity. It invites persons to participate in God’s mission to save the world. This means that we ourselves must be saved and transformed into the sort of persons that can follow Jesus into the darkest places on earth because we have become persons of the light.
At this point in history we don’t need a call to mission that tells us to do things. We still need a call to mission, but we need one which upsets our presuppositions and gives a call to radical discipleship – the way the Great Commission did 200 years ago, or the call to unity in Galatians did for the early church.
Israel had fulfilled its salvation-historical role with the conclusion of the salvific work of Jesus the Messiah in his death on the cross, his resurrection and his exaltation to the right had of God. Israel will enjoy the fruit of this work as 'primus inter pares' (cf. Rom 1:16).
You see, the problem with an invitation is that you can politely decline it. You may be being ungracious or impolite, but you can always refuse an invitation. If you decline a command, you are being disobedient, no ifs, no buts.
A quick plug for a very good book. Did I mention that it is free?