Liberté, égalité, fraternité to cut it short. You can also read Voltaire if you have more time. Religion is absolutely not part of the founding principles of the French Republic. France may be a traditional catholic country, the Republic is (annoyingly) fiercely non-(anti?) religious
"[...], where are they themselves rooted? what are they based on? what is their reference or inspiration? assuming you'd dare point to one, is it contradictory? does it justify their opposite or non-existence just the same? if you are unable or unwilling to answer these questions then you are in no position to state what or how a civilized and progressive society is supposed to be, let alone offering alternatives to existing foundations or references"