Perhaps an unpopular take, but my suggestion would be to think if you can come from the perspective of love: do you love these people, and care about them, though they've believed lies? Can you converse with them with respect, listening to why they feel how they do, and be patient to bring truth only to help them, not to self-righteously vindicate yourself?
Then again, this is the internet, so if you jump in, post inflammatory memes, pat yourself on the back for being so clever, and jump out again, and show us the results; perhaps I'll giggle along with the rest of us.
For a different take, you might like to note that part of the effectiveness of propaganda is not a good rational explanation but repeated asserted lies. Jumping into a different set of assertions can help pop you out of ones you've wrongly believed from your own background - but it can also wear you down to believe, or half believe, what the other community is saying even if it's without merit. Keep a check on the things you read: What's the actual source behind this? Could these be repeatedly misconstruing that thing in the same way (so they look coherent but aren't)? Is there some useful truth in here I missed? And is there a subtle lie attached to the truth? And there's lots of other helpful questions you can ask: but keep a sensible head and be prepared to step back and look at something else.