People are different. People are imperfect. These two axioms don’t need my support. You know they are true.
If people are imperfect, then every person is probably wrong about at least one thing.
If people are different, then people are likely to be wrong (and right) about different things.
Ergo, any two people almost certainly disagree.
If you want honest, real relationships, learning to think someone is wrong and still be friends is a necessary skill.
If you want honest, real, relationships, learning to tell someone they are wrong, and expecting them to be grown up enough to not take it personally, is a necessary skill.
If two people both have both of these attributes, they can be real, honest friends. If they do not, they can only be friends by lying through their teeth or trying to force one-another into a pigeonhole. In either case, they are not real, honest friends.
One final factor, with regard to me:
Despite my online persona, I hate conflict. It takes thought and emotional energy I prefer not to waste. I will tend to nod and smile in person even when I actively hate what is being said.
So if I tell you that you are wrong, it means I am willing to spend thought and emotional energy on you. Which, in turn, means you are unusually valuable to me.
I can understand if you have missed this fact. The reverse concept, that all contradictions are personal attacks, that telling someone he or she is wrong is only ever done out of arrogance, is the default position of the post-modern West. You’ve eaten and drunk and breathed that concept since you were born.
But now I have told you.
If you choose to act like a post-modern child instead of a pre-modern grown-up, and take offense to my disagreement, I cannot stop you. But though you remain worthy of my love, you will no longer be worthy of my respect.