Many of the early leaders of the Zionist movement, such as Theodor Herzl, were secular or atheist, emphasizing Jewish cultural and national identity over religious belief.
In contemporary Israel, about 45% of Jews identify as secular or non-religious, and secular Zionists—who may self-identify as atheist or traditional—constitute roughly 55% of the population.
Maybe they use it as a cover to justify their crimes against humanity, but as another person said, blaming it entirely on religion is a cheap deflection that tries to overshadow the root causes of such madness. When reading your first comment, I was somewhat in agreement, but your last one makes it seem like religion is the main reason for their deeds, as if the other 7 billion religious humans act the same way they do…
I would argue that even though they identified a bit with Christianity, they weren’t religious. The nazis used lots of christian symbolisms and rhetorics due to cultural heritage as a way of garnering support.
But, stating that nazis were religious as in they adopted clear doctrines and rituals is fallacious, their philosophical beliefs were more akin to pantheism than anything else.