It might be that D is just looking for a way to build up his self esteem, his wife is most likely threatening that and unfortunately he may just be on the defensive to anyone else that pokes at him. That is a could be, or, you may be seeing "why" his wife is having a hard time with him. ( you might be able to relate with her more than him OR you may be able to relate with him if it's the wife that is bringing this out in him.)

However, this group is interacting under an ideology and they are reading or want to find books or literature that validates that ideology. If you bring in any ideas or literature that questions that and expect them to accept something that challenges the very thing they prefer to "validate", then they are not going to be very receptive. This will happen with "any" group that relates under an umbrella of some kind of overall "belief". These groups typically have some kind of gate keeper (R) that will behave exactly the way you are experiencing this isidiousness.

What you are seeing is how these different individuals have "challenges", and in that alone, they get together under the umbrella of a general belief that has a base of agreement while they also work through their individual challenges. If anyone questions or disagrees or tries to disprove that "base belief", they will have to face the scorn of the gate keeper. That is how human beings are.