Of course it is troubling. The thing is, that Europe is a continent of immigration if it wants to survive. The declining birth rates are a fact and nobody can change those realities.
In the past many faults were made in the selection of those who are allowed to come to Europe. Espechially the former colonial nations opened their boarders to the people of their former colonies without checking them on their suitability. This was a major fault.
The more the muslims will riot the more the pressure is rising to deal hard with the problem. Therefore the recent torching of cars wasn't that bad. It woke up some lazy politicians to do something on it if they want to get elected in the future. There are some very easy things that can help:
1. Throw the fanatic hate mullahs out.
2. More capitalism will help Europe to give those rioting kids the jobs they need to be satisfied with themselves. People who work do not waste their time in torching cars.
3. Help the muslims to reform islam into something we all can live with. They need somehow a sort of Martin Luther to clean up with all this BS.
4. Help Christianity and Catholizism to its suitable position the the European society again. Therefore it will be also nessecary to reform some basic things without falling into the sort of relativism Benedict rightly criticized.
I have great faith in our people to deal with new conditions and to open the path to a good future. There are several reasons why I stay optimistic:
1. It is quite simple - Christanity is a much more interesting religion than Islam. Everyone who reads Bible in comparison to Koran and the Hadiths will find out that Muhammad was a bad plagiarist. He falsified Bible into a hazy shade he called Koran. This is something that has to be understood to take the recent trys of proselytization in Europe even-tempered and cool. It just doesn't work to change christian Europeans or even atheist Europeans into Muslims. Nobody execpt of some unsatisfied Idiots is interested into their BS.
2. Europe is in a major change in the moment. Among the important countries (France, Germany) it seems that the socialist gouvernments are replaced by something more capitalistic. Since we still have one of the biggest industrial frames within the whole world combined with a well educated workforce there is good chance for a major upturn.
3. In the long run our religion will find a suitable place again. There is much more grassroot spirituality among Europeans people from America could ever think of. In my comunity i.E. you will find a stable Christian basement. West (espechially south) Germany and rural France is deeply Christian soil. Of course there are areas were religion nearly vansihed (east Germany, Czech Republic, some parts of the big towns), but they are not representative for Europe.
Greetings from Lake Constance :-)