1 Corinthians 1:10
I appeal to you, brethren, by the name of our Lord Jesus Christ, that all of you agree and that there be no dissensions among you, but that you be united in the same mind and the same judgment.
Many people have the notion that Catholics believe in Church unity that is summed up in the words “That which is not forbidden is compulsory.” There seems to be the notion afoot among those who know nothing of the Church that any disagreement among Catholics about anything is a refutation of the claim that the Church is One. But as G.K. Chesterton observed, the reality is that Catholics are really only asked to be in unity about a few cosmic truths (largely summarized in the Creeds and few dogmas of the Church). They are free (and rather enjoy) arguing about everything else. But they are required to argue in charity, not in arrogance or hatred if they are to do it as Catholics. As was said long ago: “In essential things, unity; in doubtful things, liberty; in all things, charity.”