The European invasion by Middle Eastern refugees (no they are not all Syrian) is being made by mostly males between the ages of 18 and 45. Thes Muslim men are coming to Europe to conquer it not to seek asylum.
The current birth rate of Western European nations is 1.00 to 1.50. The Muslim birthrate is 3.50 and will be more in the countries invaded. Muslim men will mate with European girls and raise Muslim children at such a rapid rate that it will only take decades for them to be in the majority. Once in the majority Muslims will institute Sharia Law in all of Western Europe and the takeover will commence. The local native population will eventually be bred out and those that survive will be forced to adopt Muslim culture or be beheaded. The practice of Christianity and Judaism will be prohibited and the rights of women taken away.
This takeover can be accomplished without a shot fired.