Another perspective might be: instead of addressing the issues he raised, you dismissed him. He's white, he's male, he's cis, he's conservative, he's in a blue collar field, he's in a predominantly male field, which (Henry says) is a place of black and white thinking.
Mightn't Old Friend have good cause to feel invalidated and dismissed and marginalized by you and Henry? You have literally dismissed him or anything he has to say, not on the value of the ideas, but on his race, gender, and job.
Another fair question is: Is this the point of conversation and friendship? To always validate the other? Sure, sometimes we want that, but is there room for honest conversation and sharing of ideas and perspectives? Or do we just remove everyone from our lives who doesn't agree with us?
And if the point of conversation was validation--shouldn't you also have validated him? By his own words, he felt deliberately misunderstood, so I doubt he felt validated, either.
In what way did he scare you?
At this point, you need to decide if you value him as a person or if you value maintaining friendships only with those who agree with you on everything.
It really sounds like you didn't read my post at all.
One of the things I enjoy about this friendship is THAT we don't see things the same way. I enjoy having discussions with him, because up until this point we really could come at the same issue from totally opposite sides and leave with a better understanding of the other's position. Old friend is an intelligent person and I have always enjoyed our conversations. I love to argue (and by that I mean discuss), so the echo chamber is not a place I generally reside
The part where it became problematic, was as fuchka said, where I felt that he wasn't listening to me at all or valuing what I had to say. I'm totally cool with him thinking polyamory is a sin or whatnot. What I'm not okay with is being treated like I don't even matter as a human being.
I gave those elements of his background for further understanding. Most of the time, it's not relevant in my interactions with him which was why this particular conversation knocked me for such a loop that I'm still upset about it a week later. I have never felt like I HAD to notice those things about him before, relevant to his actions.
I am happy to listen to Old friend whenever he wants to discuss things and he can hold whatever opinion he likes as long as he remembers he is talking to a human being and that my opinion is equally as valid as his. That was the part he wasn't fulfilling. I don't think I am expecting too much literally from a stranger, let alone someone who has been in my life dearly for 20+ years.