Maybe you can try the Prayer of St. Francis approach.
Instead of trying to be understood by them, get them to reveal what their thoughts are on various issues, drawing them out by remaining non-judgmental. Oh Master grant that I may never seek … [so much] to be understood as to understand.
The more you draw him out, the more he will reveal his strengths and weaknesses in his reasoning to you and to himself.
This doesn’t mean you agree with them, you tell them it is interesting and then ask questions like, “well, that is very interesting but how do you deal with this?” If they run up against a brick wall, don’t push them or gloat. Simply smile inwardly, say something distracting, and maybe raise a beer mug as a toast. OK, so maybe you don’t drink beer.
It’s also OK to say, “that’s interesting, that’s not how we believe, but I think I can hear what you are saying.” Just don’t take the position that you are Judge and Jury for their ideas just because you happen to be a member of the team which holds the Truth. If you resent them or pity them for their false beliefs they will detect it.