This is what the Islamists are up to and it's why people are concerned. It's a minority of Muslims but it's still a problem. Combined with the fact hundreds of people in Europe have been murdered in Islamist terrorist attacks in the past two years are you surprised there's anxiety and a sense that the Islamists have nothing whatsoever good to contribute to society.

Then you have the burqa and the niqab - the Islamist's dress code for females. 

Making things worse, extreme or regressive-left voices in western countries seemingly welcoming the craziness and viciously attacking anyone who raises issues/concerns and calling people racist Islamophobic bigots if they question anything.