The IRA murdered HUNDREDS of British civilians. I'm not arsed what their 'motive' was as it was just as defunct as using religion or referring to your 'homeland' as the crazy guy in the video did today.
But your point was actions representing an entire culture. The IRA (split from the real IRA around the 70s I think) represented a group of northern Irish wanting independence after being at war with the English for decades, and declared war against the English. They never represented every northern Irish man.
Muslim extremists do their acts for their religion as part of a god given right. In turn causing people to be fearful of people who practice that religion worrying that blinded belief can lead to violence.
I'm not defending either or justifying it. I'm separating the two, and the reason why there is just gonna a different types of bigamy and race/religious hate.
All religious beliefs get on people's goat because it's grounded in falsity and nothing tangible. So commuting crimes in the sake of it is purely incomprehensible nowadays, as it pure belief in it