It's been stated many times that the only analog to this willing surrender of sovereignty is when the Roman Empire brought in the Goths, and for precisely the same reason as this immigration madness is taking place: the assumption that a new population would assimilate enough to defend the old culture. It doesn't work that way.
A belief system like Islam may grow and expand itself by subjugating other cultures. Eventually though, religious adherence to such a system will necessarily bring about its own demise through its inability to adapt and from suppression of innovation by its individuals. It's much like a mindless culture of bacteria that will eventually exhaust its food supply.
The Almighty gave us the best Manual on how to live together on this planet. It's why cultures based Judea-Christian governments do so well and makes such huge strides in humanities, sciences, etc.
The world needs to treat Islam like it treats Nazism, as Islam is much worse. Islam is responsible for, in some estimates, the deaths of almost 300 million people. This figure doesn't begin to account for the untold millions who've been beaten, maimed, raped, tortured and made to endure a lifetime of slavery.
Islam, without doubt, is far worse than Nazism, Communism, and Fascism combined. We have two long term choices: Contain Islam or be destroyed by it. John 10:10 "The thief comes only to steal and kill and destroy..."