I went to look for three specific incidents I can remember happening in the last decade, and in the process stumbled across
this article that includes two of them and a bunch of others, some of which I didn't know about.
I don't think they've been getting support from any Pope, but I haven't heard any approval from Islamic leaders either, and if relgious heads have been supporting the terrorism of radical muslims I'm very interested in reading about it actually
Yes, other Christians absolutely are finding sympathies. I've had neighbors talk to me about how some of these occurances just happened as a reason to turn people on their religion and that they believe the people that committed these acts were good, solid youths at heart and some other bullshit you tend to just eye roll out of your head because of the level of "uggh no" you experience upon hearing them.
And, if I'm remembering right, there are various churches across the states that also support the acts of these people. They're usually just dismissed as being radical or associated with Westboro and the like.