Um, I'd cite my source, but I can't post URLs yet, apparently...
There was a lot of historical momentum behind the holocaust. The Jews were scattered by the Diaspora of 607 BCE (Babylonian), and 70 CE (Roman). The consequence of this is that they were a significant minority in many predominantly Christian nations during the Dark Ages and beyond. Most Christians of the Dark Ages had little tolerance of those of a different faith, thus putting any non-Christian in their midst in danger.
There were, of course, problems particular to Jewish-Christian relations. Myths of blood libel, for example, were rampant from the 12th century to the mid-20th century, and led to pogroms.
Some would have argued that there is a certain degree of pretention and entitlement in Zionist ideology that rubs people the wrong way, though that’s a politically incorrect idea and I’d consider it a minor factor (but not
because it's politically incorrect).
More significantly, there was the dynamics of money lending while charging interest, formerly known as usury and a sin to Catholics but not to Jews. (source can be found by looking up usury on wikipedia).
Lateran III decreed that persons who accepted interest on loans could receive neither the sacraments nor Christian burial.[3] Pope Clement V made the belief in the right to usury heresy in 1311, and abolished all secular legislation which allowed it.[4] Pope Sixtus V condemned the practice of charging interest as "detestable to God and man, damned by the sacred canons and contrary to Christian charity."
The Hebrew Bible regulates interest taking, but interpretations vary widely. One understanding is that Israelites were forbidden to charge interest on loans made to other Israelites, but allowed to charge interest on transactions with non-Israelites. However, the Hebrew Bible itself gives numerous examples where this provision is evaded.
Cato in his De Re Rustica said: "And what do you think of usury?" - "What do you think of murder?"
But one must always consider that usury, in historical context, has always been inextricably linked to economic abuses, mostly of the masses and of the poor; but sometimes of the financier and royalty, as bankrupt royalty has led to many a demise, thus frowning upon lending at interest or for a euphemistic "just profit"[clarification needed]. The main moral argument is that usury creates excessive profit and gain without "labor" which is deemed "work" in the Biblical context. Profits from usury are argued not to arise from any substantial labor or work but from mere avarice, greed, trickery and manipulation. In addition, usury is said to create a divide between people due to obsession with monetary gain. Most importantly, usury is the derivation of profit from biological time, which is linked to life, considered sacred, God-given and divine, leading to excessive worrying about money instead of God, thus subjugating a God-given sanctity of life to man-made artificial notions of material wealth.
As the Jews were ostracized from most professions by local rulers, the church and the guilds, they were pushed into marginal occupations considered socially inferior, such as tax and rent collecting and moneylending. This was said to show that Jews were insolent, greedy usurers. Natural tensions between creditors and debtors were added to social, political, religious, and economic strains.
Thus we had an unfortunate quagmire created by a conflict between the papacy and pragmatism. People in a developed economy need loans, but who is going to loan money when one cannot charge interest without going to hell? The Jews, prohibited from holding public office, entering guilds, and the like, found their niche in money lending. And they were despised for it. It wasn’t due to an avarice particular to their race, as eugenicists would later put it, but a consequence of the social facts of the middle ages that had ramifications extending well into the 20th century.
This ugliness was compounded by pseudoscientific philosophies that gained traction in the late 1800s. Particularly problematic was the eugenics, which was derived from a misinterpretation of Darwin and his peers’ ideas. Other problems included Manifest Destiny, imperialism, and ultranationalism. Hitler could easily have cited America’s successful eradication of the Native Americans and enslavement of the Africans as proof that Aryans were superior and should exterminate (Jews and those who oppose Aryan dominance) or enslave (other non-Slavs) those inferior to them to make the world a place for Aryan masters.
Make no mistake, there was nothing unique about Germany that caused the holocaust. They had a heavy concentration of these terrible ideas - but so had Imperial America, Imperial England, and Imperial Japan. The difference was contextual, i.e. the spark that was Hitler’s charisma/insanity and a perceived need for a scapegoat after the misery and shame in the aftermath of WWI. The Jews were a convenient target, and were painted as traitors in addition to their previous label as swindlers. The truth of whether any significant numbers of Jews were traitors or not would have made no difference and obviously should have been irrelevant to the fate of the entire group.
Still, we have to wonder how so many otherwise normal people can stand by and let millions get killed. I’d recommend reading Obedience to Authority by Stanley Millgram to get more insight on that.