You didn't study your history, comrade! Communist orthodoxy believed in a historical inevitability that overlapped very closely with a sort of man-made Divine Providence. The Nazis had their own set of religious and spiritual motivations, their racial destiny and so on.
They differed from Abrahamic religions in the sense that they expected "victory" in this world and in their time, as opposed to vague posthumous compensations and end-of-times prophecies; but they did believe in a "greater power" manifesting itself in their successful deeds.
> backing down in Syria will only embolden them.
That's a false dichotomy. The problems in Syria won't go away with bombs, and it was manifestly stupid for Hollande to join the party willy-nilly, especially after having experienced first-hand the inefficiency of his security apparatus. What is needed is a real agreement between the real power brokers (Turkey, Saudi, Russia, Iran) to cut off the crazies for good. We need hard diplomacy, not hard policies.