18 Some of you have become arrogant, as if I were not coming to you.
Paul addresses the arrogance of some of the Corinthians. Religious and spiritual elitism is a curse. You think you are better than someone else because of what you think you know or experience. It colors your view of others. An example Jesus told was the publican and the sinner. Here you have the publican and the sinner. The Publican is congratulating himself on his piety, words and religious service. He is also looking down on the sinner who is just repenting. Jesus said the sinner well be heard over the publican because God hates religion unless it is taking care of the widows and orphans and keeping oneself polluted or stained by the world.
They also mocked, slandered, and criticized Paul because he was far away. They thought that Paul would not make the long trip back to Corinth. While the cats away the mice will play. Paul was about to blow that theory.