It is a fallacy to believe that an individual perspective is enough, that as long as they do not commit crimes everything is fine.
Because the more Islam spreads, the more our freedom recesses. The more Islam spreads, the more our culture and values recess, and we have the right to choose. Today we have millions of people who live in areas where it is dangerous to be gay, to be Jew, to wear a skirt or to criticize Islam, where brown people are forced to behave as "proper" Muslims. How could we use police forces to detect and arrest the two millions of assholes who exert this ordinary social pressure on a daily basis, those permanent little threats and gradual intimidation by so many people, this heavy social pressure? Especially in blocks where the police is easily targeted, where talking is seen as betraying the community? Liberalism cannot solve this.
And beyond that, what about the long-term, when former immigrants give birth to citizens who then vote for retrograde values? They will not break any law when they will change our laws.