Not exactly sure what you're trying to say. As I understand it, integration = a lack of terrorist attacks, and that = safety. Can you clarify?
Also, how do you think integration should be implemented?
I consider a few hundred dead / year in Europe through religious nuts acceptable.
Parallel societies are not acceptable.
Around 1992 I had a discussion with somebody of Turkish background, probably first generation born in Germany. I asked why a Turkish boy can have a German girlfriend, but his sister can't have a German boyfriend. He said it's not acceptable in his culture.
The Turkish never made a fuss about religion. There were plenty of anti Turkish jokes, none based on religion.
There was a "Golden Age of Islam" when the upper class were traders with a wide experience of travel, when European feudal society had the leading classes far more backward.
So while I am prejudiced against tribal religions (as well as tribal societies), I generally believe economical, not religious factors dominate culture. However if immigrants feel rejected they may take pride in their "own" culture.
Time also plays a role. Europe's exit from the middle Ages began maybe in the Renaissance. But then homosexual rights improved only very recently. So change in our mentality took a few hundred years.
IIRC the US in the first half of 20th century had a policy to strengthen US identity. Immigrants even after few generation still had identity of country of origin. The US had to get rid of it.
The Turkish were invited to Germany for simple jobs, so most may have been from poor, backward regions and background. That didn't make integration easier.
I had a granny born around 1900. Already when I was 14 or so I found her loving, but too simple minded. Her mentality and my mentality were very different, and she died during my adolescence. Her views on sex before marriage or gay marriage were incompatible with today's views.
Forget other religions and foreigners. Suppose we can invent a time machine and bring three million French of 1900 to today's France.
Should mainstream society try to teach their children today's way of thinking or should we accept that their children view the world different?
We take three million Germans with 1900 mentality.
According to political correctness cultures are not better or worse, only different. So what should be wrong with it?
I am sure the Turkish have some cultural treasures. I'm willing to learn, provided they can argue their case.
They can also refuse mainstream culture, provided they can argue their case.
And if Muslims can credible argue that girls are not forced by their family to wear head cover, I have no problem with head cover. So head cover for a Turkish background girl in Germany is not the same as head cover for an Arab background girl in France.
A Muslim of a collective society may say the head cover is not for discussion. So do I.
Collective and individualist societies have incompatible views. From my experiences in India, but also from literature, I believe collective societies are rather unhappy societies. The West exaggerates with individualism and I'm happy to listen to criticizm. But overall I believe personal freedoms lead to more happiness.
Of course Western society also has people who prefer the collective over individualism. It is to be hoped that sport events satisfy their needs.
Unfortunately the collective mind is prone to a " we against them" mentality.
Are Front National/ AFD supporters the Turkish/ Arabs of Europe?
Being immigrant myself in a collective mentality society, do I take too much pride in the culture of my origin? The usual argument is that migrants should adapt to the culture of the host country. Well, I believe it's a mind that leads to unhappiness. Indeed now is the first time most Indian children enjoy at least 10 years of education. And the young generation clearly tends to more individualism. They also don't like the extreme collective mind. Obvious it can't be changed in one generation, but developments are hopeful. Similar third generation Turkish born in Germany are more agreeable than their ancestors.
Why to help the old mindset by showing tollerance to a thinking that oppresses individual choice?
Do I argue like a Taliban?
That's possible. As I said, I believe in Weltanschauung.