FWIW it's virtually impossible to determine the open-mindedness of someone from afar, and to make assumptions about their ability to even consider other ideas seems like a way to insulate oneself from difficult ideas - by declaring that someone is incapable of an honest evaluation of your perspective, it prevents your perspective from being scrutinized (which, ironically, could lead to being close-minded if you're not careful).
A parting thought: most people
(a) can be reasoned with if not attacked - you can find common ground and have a good discussion with nearly anybody
(b) on every "interesting" social/political issue there are intelligent and thoughtful and just really great people with nuanced and reasonable perspectives all across the spectrum - the extremist nutjobs on the fringes are wildly outnumbered by pretty normal people
So as a random dude on the internet, just a friendly warning that if the above strikes you as untrue (e.g. if you believe large chunks of people are intolerant or incapable of being reasoned with, or if you see a difficult social issue as pretty much black and white and can't understand why so many people don't get it), then there's a good chance that you've been duped and have been sucked into a form of modern tribalism.
I am assuming that his Christian perspective is similar to the one I had. My experiences with Christians since have reinforced this expectation.
Does that help?