Oh I agree... All cristian, muslim and other religious folks should keep the religion to themselves and behind closed doors.
I dont know anything about the "Brookings Institute" but It will be houndreds of years before the Muslims can "overrun" my country even in the remotest theory. You said Europe so i gather you mean all the individual countries in Europe. The problematic muslims are a minority and its usually only the first generation and some in the second that spawns kids like there is no tomorrow. The second generation and beyond are too fond of western values and get indoctrinated with our culture. They get about the same amount of kids as the rest of us.
All that beeing said, I would love it if they closed the borders tight and only let in those who have been severly prosecuted in their home land, or non-religious people with skills and education.