The country, he said, now has “one of the more expansive counterterrorism laws in Europe, and in the last few years they have only added to it.”

That prosecutorial energy reflects the public preoccupation with terrorism and the extent to which France still feels itself under threat.

“We are fighting against Salafism, that is to say extremism, religious fundamentalism,” President Emmanuel Macron said in a television interview this week. “I want to be very clear about this: This is a problem in our country.”

Yet, if anything, the trial this week confirmed that it is French society’s marginals, the unemployed and the psychologically unstable, who are particularly prone to sudden bursts of radical Islamization — and not its Muslim pious.

The continuing debate in France between these two explanations for jihad has not been resolved, but real-life incidents consistently throw up more examples of the former than the latter.

And so it was at this week’s trial.

“The ambience was very much in favor of the Islamic State,” one of the defendants, Hamza Mosli, 29, who lost two younger brothers in Syria, testified.

Having sprung to prominence, Lunel was invaded by journalists around that time, even as officials and citizens professed shock and disbelief that 20 sons of the town had left for jihad, at least eight having died. The imam at the mosque was censured for not taking a firmer stand against the departures.