This section's main subject is how a minister should approach preaching the gospel. But notice, when we distill His words down, Jesus is saying that, for a minister, preaching the gospel is non-negotiable. In the vernacular, He says to His ministry, "If you go into a town, and you find worthy people to stay with, preach the gospel to them. If they accept it, great. Stay there and preach for as long as you need to. If they reject it, great. Pick up your belongings, dust off your pants, and go to the next town. As a minister of God, you are not preaching for the sake of numbers, or to receive praise from the people, or to make money, or whatever. Preach the gospel. Period."
The minister's job is to preach the gospel. If the people accept it - wonderful. If they do not accept it - well, they will get their reward. The ministry does not have to waste its time in places where the gospel will not be accepted. God does not want His ministers to throw pearls before swine, as it were. He wants them to find those who accept the truth, who want to believe the truth, who are willing to support the truth, who want to help in getting the truth out. And if none are to be found in a particular place, they are to move on. Evidently, God has not called anyone there.
But the truth remains the same. The message must be preached, and it must not be changed. Jesus is pretty hard-nosed about this. A minister of God is not driven by numbers, nor by contributions. He should not be driven by anything designed to make him look "good" because he should not be in it for his own glory. He is in the ministry because he desires to preach the gospel and glorify God. That is what his Master has told him to do, and he is a man, a servant, under authority.