While I agree with this in theory, I'm going to point you to this fascinating piece on some of the ongoing problems that the French tradition of republican laicity is facing from Muslim immigrants, as a general illustration of the conflicts involved:

http://www.nybooks.com/articles/archives/2015/mar/05/france-...

In summary: the very culture of tolerance and openness towards others itself is sometimes threatened by those it wishes to welcome, and that's a hard problem to solve.