A way of explaining it to Americans might be by analogy to immigrants in the US. Imagine Hispanics but with Hispanics numbering only half the number they do and with far lower immigration rates. Like Hispanic immigrants, Arab and African immigrants do have higher birth rates than native born Americans. Like Hispanic immigrants that drops off sharply. The gap however is smaller in both instances than with Hispanics and whites in the US, and again, the numbers are far smaller. So perhaps we can take Asians - a somewhat smaller proportion of the population than Muslims in France, but similar or higher immigration rates. Like Arabs and Muslims Asian immigrants have more kids than native born  (and like them, often more than in their native countries), though the drop off with US born Asians is even sharper than with French Muslims.  From a demographic point of view, speaking of the Arabification of France is about as absurd as speculation about an Asian majority in the US.

As far as religion goes, French Muslims are much more likely to be devout than French non-Muslims, but much less so than American Christians. That goes across the board. I'm too lazy to look it up now, but I believe fundamentalist beliefs are shared by about twenty percent of French Muslims. Twenty percent of seven percent. Sharia isn't coming to France anytime soon. And potentially violent fundamentalists are a small minority among that group. Something for the security forces to keep an eye on, but in the same way that the violent radical anti-abortion groups or white supremacist ones are something the FBI takes an interest in. That's it. One annoying public security issue among many.

What France does have is an unpleasant intersection between racism and class structure. But that should be pretty familiar to Americans. I personally believe that France should consider adopting some of the American tools against racism (affirmative action, specialized bureaus aimed at enforcing the laws against discrimination, class action lawsuits), but the reverse is also true as regards anti-poverty measures.

In general the 'Eurabia' phenomenon is racism pure and simple. We've seen it many times, applied to various groups, in both Europe and the US. Plus ca change...

I just have to recall ehre that reality does not matter... narratives ahve life ont heir own.. and if they perfectly fit different pieces that otherwise would break a part , theya re kept until a disonance comes...

The republcian party uses this fact all the time to present their candidates as mainstream with the help of the big media.

A pleasure

I therefore claim to show, not how men think in myths, but how myths operate in men's minds without their being aware of the fact. Levi-Strauss, Claude