Christians can be persecuted like any other group, and they are in countries like Saudi Arabia and have been in the past - But they can't be persecuted when they are the majority of the population and simultaneously hold most institutional, economic and political power. Christians can only be discriminated the same way white people are marginally discriminated. Persecution denotes open aggression against a group or person and is worse than discrimination. It certainly doesn't apply. French laws are not exactly the best example of secularism
That's laicité. I think a 100% secular society is an impossibility because we would have to abolish Christmas and take measures that we can't possibly if we desire freedom, but a rational level of secularism is desirable. Nothing will stop the majority of people in my country from being Christian and thus Christianity having higher cultural influence, so secularism isn't 100% in effect, but it is enough to allow me to scream "Fuck Jesus" without being arrested.

Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you