The French educators want to ban Muslim girls covering their hair at school, because they believe that "in a secular society, children should not be allowed to flaunt their religion". To understand why the French educators think that way we need to examine the Christian attitude to "sex", how this attitude has lead to the "modern secular permissive society", and why Muslim women cover their heads and bodies.
The traditional mainstream Christianity, and especially the Roman Catholic Church, saw any form of "sex" as sin. Celibacy was seen as the highest of virtues and a way of seeking proximity to Jesus (God, or the Son of God). Sex (within marriage) was allowed to those who were not close to Jesus (God, or the Son of God), as a concession, but it was something "dirty", something to be ashamed of, something to seek forgiveness for.
Christianity was based on a set of "dogmata", beliefs which had to be accepted as true without questioning. The main dogma was the "trinitarian doctrine", according to which Jesus was the Son of God, whom God sacrificed on the Cross, as an act of Redemption of Mankind from sins. At the same time Jesus himself was believed to be God, and Mary was God-the-Father's Bride, and God-the-Son's Mother. The Holy Trinity itself was seen as One God, and consisted of (1) God, The Father, (2) God, the Son, and (3) God, the Holy Ghost.
Anyone who would dare to question this dogma was a "heretic", and would be tortured and burnt alive. The Christian Church exercised a high degree of control over the lives of people in the Medieval Europe. It also promoted the belief in punishment of sins in Hell. It was also possible to buy from the Church an absolution of sins, and thus an admission to Paradise.
In 16th - 17th centuries, the Europeans started rebelling against the dominance of the Christian Church, and in some countries this lead to reformations (changes in the dogmata, and the status of the Christian Church), and in some countries (like France) to revolutions and establishment of secular government, or "separation between Church and State". By the middle of the 20th century Christianity had lost most of its influence on the life of the majority of the Europeans.
But the Christian morality still continued to be part of the European thinking, and this was especially true of the attitude to the Human Reproductive Process ("sex"). While the Europeans no longer believed in being punished in Hell for their sins, they still felt ashamed to "talk about sex", and saw "sex" as something "dirty", and as "fun" - "dirty fun". Parents would seldom talk to children about sex, who were expected to discover it when they became married. But men would occasionally visit "naughty women" to "have some fun". Also marriages arranged by parents were common, especially among the property-owning "classes". This continued to the middle of the 20th century.
On the whole, the view of religion in Christian Europe was "worship of one or more human-shaped gods, and a set of dogmata and superstitious beliefs". This view was based on their own experience of religion. And, as the Europeans could no longer believe in a man-shaped god, they rejected their Christian religion as "unscientific", and together with the religion the morality which was based on that religion.
By the second half of the 20th century the traditional parental control over children became loose, and the political state was assuming a greater role in education. Sex liberation became one of the major social trends - it became "socially acceptable" to have sex outside of marriage - and this lead to wide-spread "unwanted pregnancies" and "sexually transmitted diseases". The response of the state education system was "sex education". Children were encouraged to use condoms and contraceptive pills. Homosexuality was decriminalized and became socially acceptable. It was promoted by the media and encouraged at school as part of "sex education". Legislation encouraging homosexual marriages was introduced.
This society deprived of all sexual morality has become known as "the permissive society".
While the modern "western" way of attempting to prevent sexually transmitted diseases and unwanted pregnancies is use of condoms and contraceptives, the traditional way known to Man for millenia, has been the institution of heterosexual marriage. Marriage is a social institution regulated by laws and customs, the purpose of which is to restrict the Human Reproductive Process (Sex) to the framework of a family unit. The Muslim practice of women covering their heads and bodies is aimed at the preservation of the family unit.
Contrary to what many people believe, hijab (veil) is not a Muslim uniform, nor does it have any 'spiritual' meaning. It's purpose is simple and very practical, and it is clearly stated in the Qur'an (33:59):
"O Prophet! Tell your wives and daughters, and the believing women, that they should cover themselves with their clothes. It is better that way, so that they be respected and not sexually harassed".
So, Muslim women cover their heads not "to flaunt their religion", but to protect themselves from sexual harassment. And failure to understand this fact by the French educational authorities is proof of their ignorance, prejudices and bigotry.
Had the French educational authorities made the effort to educate themselves better on the subject, they would have come to the conclusion that hijab is an effective means of maintaining healthy family life within the society and would have made hijab a mandatory requirement in all French educational institutions regardless of any religious considerations. In that way they would have reduced the spread of sexually transmitted disease, sexually motivated nervous breakdowns, and the extent of sexual depravity affecting the French society.
This would have been an example of real education, rather than of ignorance, secular bigotry, and moral corruption.