Muslims in European countries is estimated at 44 million. In World War II Hittler was exterminating Jews as he said in his superior race doctrine, that they were an inferior semitic race that did not belong in Europe. I guess most of current Islamists in Europe would have qualified for the death camps as well.
The Muslim presence in western Europe as a result of the labor and postcolonial mass migrations of the postwar period. It is certainly true that Islam became more visible in the public sphere in western Europe as a result of Muslim mass immigration to major European industrial countries in the second half of the twentieth century.