Adam Clarke on 1 Corinthians 11:19

There must be also heresies - Αἱρεσεις· Not a common consent of the members of the Church, either in the doctrines of the Gospel, or in the ceremonies of the Christian religion. Their difference in religious opinion led to a difference in their religious practice, and thus the Church of God, that should have been one body, was split into sects and parties. The divisions and the heresies sprung out of each other. I have spoken largely on the word heresy in Act 5:17 (note), to which place I beg leave to refer the reader.