It may be politically incorrect to say that Islam presents a threat to secular democracies, but it is a fact. (It must be noted that those professing Muslims who practice a liberal, water-down version of Islam are not a threat. I use Islam to refer to what it is, not what some have made it. Real Islam is the teachings that are found in the Koran and the Hadiths). The headscarf ban is a result of the inability of the French establishment to conform French Muslims to secular standards. The professing Christian and Jewish communities in France are not interested in incorporating elements of their religion into public life; the French Muslim community is. While such religious practice is not generally a problem, in Islam, it tends to be. Though I personally have no objection to, and even support, the right of any modest woman to wear a headscarf if she so chooses, that's only the tip of the iceberg as to what fundamentalist Muslims want. They want to implement an Islamic law to govern all society. (It also should be noted that these people want the wearing of headscarves to be mandatory, not optional).
France has the largest Islamic community in Western Europe, with estimates numbering at least 4 million. Though that is only about 7 percent of France's total population, a study of population demography, birth rates, and immigration rates shows that the percentage will continue to increase rather steadily in the following decades if rates remain similar. The Union des Organizations Islamiques de France (UOIF) is the unofficial umbrella group that represents Islamic interests in France. The UOIF is affiliated with the fanatical Egyptian Muslim Brotherhood, and almost all Islamic institutions in France (as in all Western countries) are controlled by foreign financing and teaching, namely from Saudi Arabia. Devout Muslims in France are becoming bolder every day. Though the French government is reluctant to discuss it, France has been the seen of thousands of anti-Semitic attacks in the past few years.
