Religion was an example, coming from the general category of social subgroups that carry a large impact on identity and create a sense of exclusivity, which also includes every group you described.
I would rather not see rationality marginalized into such categories, in anyone's mind.
So, you think it is bad for rationality to be a) strongly associated with a person's identity, and/or b) create a sense of exclusivity, or belonging to a group. Is that right?
Maybe I'm missing something obvious here, but... why do you think this is a bad thing?
What are your best short witticisms, suitable for use on a t-shirt, bumper sticker, or similar location? Ideally something that might make someone reading it think, or get curious enough to ask about it. Simple in-group identification is fine too, though.
For context, therufs is spending today at the NC Maker Faire making t-shirts, and asked me for suggestions this morning. As I was still mostly asleep, I wasn't very helpful.