Political identities are modern-day religions, basically.
I'm not saying it's better to be actually religious - this isn't some sob-story about how the decline of religiosity is some great evil. I'm just pointing out the parallel: that something that's consumed A LOT of human energy and attention has disappeared in 1 generation leaving a huge vacuum of meaning for most people, and people are filling that vacuum with political identities.
Doesn't this list work for both political movements and religions: shared moral frameworks, common enemies, a metaphysical value system, sense of belonging, set of virtues and sins, rigid orthodoxy, regular rituals (protests, boycotts, etc), transcendent societal goals, conflict-as-sacred-struggle, etc.
Overly simplistic, maybe; but I think I'm not too far off.