One of the reasons that Christians engage and feel a compulsion to move mission forward is because of what theologians call the “eschatological motive”. The “eschaton” is the end of the age. The world is going to end and there will be no more time to witness to the Christ and His mercy. Jesus said that the night is coming when no one can work. We, if we are Christians, want no one to slip into the darkness of everlasting despair.
Churches have stopped talking about this end time reality and it is a shame because it is a Biblical principle that we keep loose reins on the things of this world because the time is short. Mission work becomes imperative in this understanding.
Here is a part of a sermon from a seminarian who is really giving the business to his teachers and professors who have forgotten or actively sought to ignore the last part of the Apostle’s Creed that declares the Christ will come again in glory to judge the living and the dead.
“We have hacked off the Final Judgment and acted as if this world is it. We have become secularists, meaning one worlders, who have successfully denied the Final Day of Judgment even if we did not intend to do so.
This has led to taking the great teaching on justification that broke into the world at the Reformation and allowed us to be Lutherans, and selling it for pottage by turning justification into mere justice. The poor do not need a savior, they need money. Rights and Justice is what is left of this once great doctrine and so the gospel is utterly confused with re-enfranchising people with rights, empowering them so they are slaves to no one but themselves, and then helping the poor just like the Salvation Army does it—that is, with love and no idea what the Gospel is (though we will never do it as well as the Army).” 
 This is a section of a sermon by Steven Paulson preached at Luther seminary that I imagine might have made some eyeballs roll.