Heidegger's Bible Handbook: 2 Corinthians: Occasion for Writing
4. The calumnies of the False Apostles, and other things, furnished the occasion for writing the Epistle.
The occasion for the writing of this Epistle is best gathered from the order of this disputation. That is, he wrote the former Epistle, whereby the False Apostles and others were grievously offended; but others, being weak but teachable, were edified, with no small amount of fruit gathered hence. The False Apostles, undertaking to denigrate Saint Paul, had objected against him suffering, falsehoods, affected tyranny over the Church, imposture, and distortion of the word of God. But the pious saw to it, that his honor might be continued to him, and his authority kept intact. So Saint Paul had to repress the vanity of the former, and also to look after the infirmity of the latter.