You should check your numbers. There are about 3-5 % Islamic people in europe and mostly as secular as the other religions
https://www.cia.gov/library/publications/the-world-factbook/index.html
I have read that there re 20M+ Muslims in Europe, which would be closer to 5%.
Nonetheless, the issues are not so much the number right now, but how many Muslims will live there in 1 or 2 generations, how well they are assimilating and the track record of Muslims integrating into foreign cultures. On these issues the situation is not so favorable, there are plenty of articles and books, Londistan being a good resource.
http://islamineurope.blogspot.com/
It is undeniable that several European countries will have a high percentage of Muslims in their populations in the next 30 years. What Muslims will do with this political power is undetermined, but if history stays true, it will be a problem for western culture.
schu