They are warranted---because of the fall, their sensus Divinitatus is not working properly. This is part of what giving a person over to their unbelief means. And I would say that Russell's problem is grounded in a bad understanding of language and meaning. His analysis is unnecessary. The point of Russell's paradox is precisely their existence. You and I maintain that it is irrelevant, though, for entirely different reasons. I think you have confused "making sense of" something with understanding it. One may be false in how one makes sense of something. If and only if the belief in question was reached by means of formal logic. If it was reached by means of the senses, or some other form of deduction, it is more likely that a de facto critique is needed. I'm simply pointing out that the rank and file even of intellectuals will find your criticisms to be either a) a logical puzzle to be solved away (the way that atheists, like William Rowe, treat the ontological argument) b) "quaint" in its reasoning c) uninteresting and irrelevant. My point is that you should probably first explain why they should care. That question only works from the outside. Inside the delusion, it's irrelevant.