When William Carey, the "father of modern missions," first tried to convince fellow Baptists that the Great Commission required them (not just the early disciples) to go out into all the world and make disciples, he was met with fierce resistance. At one meeting, an older pastor interrupted Carey's impassioned pleas, saying, "Young man, sit down. When God pleases to convert the heathen, he will do it without your aid or mine."
So anxious was the man to protect the sovereignty of God, he failed to appreciate one fact repeated time and again throughout the history of the church: When God pleases to do anything on earth, he uses your aid and mine; he uses people.
Thankfully, William Carey would have none of this man's bad theology, and he ended up going to India as a missionary, and as a result, inspired hundreds and thousands of other 19th–century British and American Christians to do the same. Today, millions in China, Africa, and Latin America claim Jesus as their Lord because God used some person, missionary or friend, to bring them the good news of Jesus Christ.