Jesus is saying that his work and that of his disciples is the beginning of the end for the forces of evil. It is not uncommon for people to resort to slander when all other efforts have failed. Luke finishes this section with the saying of Jesus that he who was not with him was against him, and that he who did not help to gather the flock helped to scatter it abroad. There is no place for neutrality in the Christian life. The one who stands aloof or apart from the good cause automatically helps the evil cause. A person is either on the way or in the way.