I have some good atheist friends that I have known for years. In general, they are very tolerant of and interested in my religion, but we have grown a little distant recently. Maybe if I try and explain what I think has happened to us, it will help you to understand what your brother’s family are feeling.
For many years, I have attended gatherings at their house (dinner parties or whatever). Most of their friends are also atheists or Unitarians, and also extremely liberal politically. In general, I had been reisgned to frequent jokes that assume the lack either of intelligence or of good motives on the part of devout Christians or political conservatives. I have understood that similar jokes in the opposite direction would be unChristian as well as poorly receivedand so in general have not made them. As far as discussion is concerned, I am not really bold enough to stand on my own on one side of an issue with a roomful or people (say, 8 or so) on the other side for very long, and for sure it would not be enjoyable, so I state my position honestly if asked, but in general try to change the direction of the conversation if possible.
This worked OK for 10-15 years or so but it has become more difficult lately. Partly this is due to a new feeling of triumphalism on the other side. The atmosphere is something like, “Now the whole country can see that we’ve been right all along about (abortion, gay marriage, whatever). No matter how stupid they are, most people see the light eventually. Except for the nut-jobs right-wing radicals.” Of course nobody is rude enough to say anything like that out loud, but the attitude is pretty implicit in the things they do say. I don’t blame them for this, because I daresay (at least in my more human moments) I’d feel somewhat similar were the positions reversed. Besides, they are in the majority, and on a private occasion, and why shouldn’t they say what they think? It’s not like we’re at work or something.
But when they’re talking about their victories, they bring to my mind not only the sadness of ground lost but also the fear of what is next. Since I’m not in a position to contribute much to the conversation, and there isn’t anyone else to say anything I agree with, I have to do a lot of silent and invisible praying to get through the experience.
It is also harder to take because sometimes it feels like the attacks are coming from everywhere in society. It’s harder to build up a shell for comments like that to bounce off of, because they are coming all the time (not just in that group of people, I mean, but lots of other places).
So, without doing anything wrong, they have caused me to feel outcast and insulted, and mostly I just don’t go to those gatherings any more. Because they are not family, I have that option. It saddens me, though, because they are good people and have been my friends for a long time. And they think (and rightly so) that they are understanding and welcoming and haven’t done anything wrong. It doesn’t mean that a visit to their house is not an ordeal for me, however.
AFAICT, they think I am being weak and touchy and over-sensitive. I daresay they are mostly right. But my pain is real even if it stems from my own weakness. The one thing all living Catholics have in common is being sinners and I am certainly no exception. The atmosphere at my friends’ home feels full of barbs to me, and it’s almost worse because I don’t dislike any of the people. It probably would be a lot worse if they were all family members that I loved, slapping me in the face all unknowing every time I came to visit, respecting me enough to think that certainly I couldn’t be stupid enough to believe that (whatever it is), so it’s OK to light-heartedly joke about that belief (but not finding out what I think about it first).
In addition, of course, sometimes some of the jokes are actually funny, so if I don’t laugh I’m being fake, but if I do, I feel like I’m betraying what I believe. In any case, I can’t come out all school-marm and chastise them for making jokes about what are, to some, very serious subjects. There really isn’t any right answer for me about what to do in this situation, so mostly I do nothing and feel bad about it.
One thing you might do is to think (not on this forum, but in your head) about what your own attitude really is to religious people. Do you think in general they are either not very smart or not very well educated? Or do you think that they are in general hypocrites? You pretty much have to think in general that they are wrong about what should be the most important thing in their lives (or else you wouldn’t be an atheist, you’d be an agnostic). Thinking that your brother (and possibly his wife) are the rare exceptions to the rule of what religious people are like is not as much of a compliment as you might think. And also if you have that attitude, it is very difficult to conceal it, no matter how much you want to. You can’t change that attitude by wanting to, either, but being aware of it can help you think more about what you say.
I hope you are all able to resolve the situation in a loving manner!