No. Despite all its horrible war crimes and crimes against humanity, Nazi Germany was not an existential threat to the European (let alone global) human civilization.
First, the Nazis did not seek to dominate (let alone conquer) the whole world – or even Europe. They only wanted to make Germany a secure, prosperous, self-sufficient and powerful nation (a global superpower) and Germans – a genuinely happy nation.
Second, Nazi Germany only slightly modified occupied nations. And third, it did not seek to destroy the Catholic or Protestant Churches (it had concordats with both). Or any other religion, for that matter.
The real existential threat to the European and global human civilization was the Bolshevist Soviet Union (and personally the “Red Emperor” Joseph Stalin).
First, unlike Adolf Hitler, he wanted to conquer the whole world, transforming it into a global Union of Soviet Socialist Republics. In other words, Stalin intended to completely destroy the existing human civilization and to replace it with the alternative – and radically different – Soviet civilization.
And, finally, he was committed to destroying all religions – Christianity, Judaism, Islam, etc. – and almost did it in his country. And to replacing it with the quasi-religious Bolshevist ideology.
Consequently, although World War II included many wars (which I will cover in the next section), its essence was to save the European and global human civilization from being invaded, conquered, occupied and destroyed by the Bolshevist Soviet Union.
Therefore, from the perspective of this essence, the Nazis (the Germans) were the “good guys” and the Bolsheviks (the Soviets) were the “bad guys”.