Why? I could never understand that.
There are so many ways to find and define one's identity. Why do people feel the need to impose tribalistic identities onto themselves? What's wrong with universal humanism?
I asked something exactly along those lines of this person I mentioned who identifies as Muslim purely as a tribal identity. According to her, it's "the way things are" and she wants to be someone who helps that tribe (which even she realizes is not homogenous) expand their outlook. I can respect that, and that is the reason I respect people like Mona Eltahawy, Tarek Fatah and some others. Though I am not cut out to be that kind of person, I think they are needed within those communities (or "tribes") if there is to be any kind of social progress in them.
Many people in the world may know intellectually that we are all human, but on an emotional level, they can't help but identify with "their people" at the expense of everyone else. This is also a result of centuries of colonialism and inter-warfare between peoples who identify with various tribes (including within these tribal groups like sectarianism). People consider their families, their closest of kin and neighbourhood to be "their people" and everyone else as "the other".
It's just a shame because a lot of times that means that even beneficial things like advances in sexual egalitarianism, LGBT rights, come to be seen as something "they" do and "we" don't. For me, I think of Audre Lorde, a black, bisexual LGBT activist as one of "my people" like I think of Omar Khayyam as one of "my people" and of Bulleh Shah as one of "my people" and Rabindranath Tagore as one of "my people".
I think universal humanism is a great idea that progressives in all communities strive to take their communities towards. Just along the way though, I guess, they sometimes feel the need to add fuel to the fire of separation, partly to stand up against those who have historically been their rivals and/or oppressors, and partly because it keeps their own credibility within these groups.
It's an interesting phenomenon and I can't say I ever really had the stomach to want to do these things "from the inside" but I think of social liberation movements like relay races - some people who are naturally critical and deconstructionist in their approach are needed to challenge and confront the dogmas that reproduce these complacence-breeding ideologies. Some people who are better at building bridges are needed to show that LGBT people/social progressives/atheists/agnostics/secularists are not hostile, alien creatures. Some people are needed within these religious/cultural institutions who are capable of helping these identity groups, ideologies and the institutions founded upon them to open up to our current views on human rights, reason, etc.
Topic: British gay Muslims seek Islamic weddings