In fact, I would go further and say that the issue is not at all about different cultures clashing, but is about what I have been talking about for a while now... clashes between different factions of each of several groups. Fundamentalists, vs. progressives are clashing within many different cultures (Christianity, Islam, Judaism and, apparently, also Sikhism), and the clashes seem to be getting more and more violent and extreme. But it is more about clashes within cultures than clashes between cultures.