Another great debate but one that easily stirs up sentiment based on personal experiences dealing with 'the other'.
There are many ways to look into the topic ranging from indifference to outright opposition. Yet, I believe this is mainly about human values first. Those same values call for realistic and rational thinking. Especially on the part of officials who are obliged, by virtue of their position, to think collectively - from a State perspective. At least for as long as States prevail.
European countries are not equally faced with an immigration problem. Immigrants as a percentage of total populations vary widely. So do cultural, historic, linguistic and religious backgrounds of immigrant communities.
It would therefore be rather poor, if not misleading, to have a one-size-fits-all approach to the challenges each society needs to rise up to.
In common, however, a notion that volumes do matter should develop. Or else we'd all consider that the world is going fully global to the extent that nations, common identity, cultural values, languages and other traits generally shared by indigenous populations are not relevant any more.
One may also argue that the world has always been a place of migrations. Dominant populations across many lands are themselves the result of many peoples and tribes who once settled in them from many origins. True enough.
The fact is that eventually a national identity was born bonded by language, religion, costumes traditions, architecture, etc.
I do not think most people belonging to one such majority population are prepared to dilute that entirely just yet. It simply does not make sense.
You may stand up for liberal values while still embracing the nation-State concept that came to be over many centuries of 'house-building' .
To my mind runaway immigration - unchecked under the pretense of generosity or sheer irresponsible political correctness - is undesirable and defeats the very human values everyone should strive to uphold, States as well as individuals.
Such type of immigration flows do pose too many unanswered questions until it is too late to properly address them.
Potentially it does store up future misunderstandings ultimately leading to trouble.
To sum it up I do not think controlled immigration endangers European societies on the whole.
Europe does need most immigrants already in and will likely take in some more in decades to come.
Uncontrolled immigration certainly does endanger societies anywhere, especially if communities espousing radically different values become so entrenched as to attempt to overwhelm local values - latus sensu.
Totally unacceptable by any reckoning.