Go ye into all the world and preach the gospel to every creature. - Mark 16:15
I am currently the middle of a class called Global Studies Survey which studies mission from its inception in the Old Testament to today. It's pretty interesting. Of course, for many years the church thought very little of their role in evangelism. Even the Protestant Reformers (i.e., Luther, Zwingli, Calvin) said very little about it. It is thought that they believed that the world had already been evangelized and that Christianity just needed to be reformed.
A Lutheran by the name of Justinian von Welz disagreed with them and asked a question in 1664 that could even be applicable in the modern day in which we live, "Is it right that we evangelical Christians spend so much money on expensive clothes, luxuries of food and drink, many unnecessary amusements and expensive habits, but yet give no thought to the spreading the gospel?"