Hm, interesting that you choose the example going that way. Not to deny that Muslims face discrimination in the West, but have you had a look at what life is like for Christians in Muslim countries?
But I'd warn against using such (and greater) injustice as an excuse. The idiots responsible for them are not the muslims who live in western countries, and any sort of collective guilt is morally indefensible (especially considering many muslims are in the west precisely because they wanted to get away).
It's also subject to what my father used to say when I tried to excuse a bad grade as "still pretty good considering how the rest did": "When did we start comparing us to others?"
Also, using the example going that way is exactly what I meant with "it's more legitimate (effective...) to criticize your own group".