We handed them a sword of invincibility, according to this interesting piece at AmRen:
After the war, the United States and its allies decided to put as much distance as possible between their nations and Nazism, which they came to define as the refusal to accept diversity. In retrospect, we can see that this set the stage for dismantling the existing particularisms in Western societies. Rejecting nationalism and distinctions between racial groups as retrograde–and even as akin to Nazism–eventually led to the Immigration Act of 1965. Repudiation of national traditions paved the way for massive immigration of non-whites into Europe as well as North America–immigration that is transforming and could ultimately destroy the victors in World War II. In the last few years, Angela Merkel has opened Germany to massive Third-World immigration as well, so the vanquished may be submerged along with the victors.
Dying societies agree on little. What do we agree on? At first Americans had positive goals, but once the WASP uniformity was broken up by the introduction of Southern, Eastern and Irish Europeans, this consensus evaporated. Diversity of any form is destructive because it removes the sense of a shared positive goal and standards.
With nothing positive to agree on, we could only come together on what we hated — or feared. If Hitler was right, our mixed-white population was also doomed. This made us take the pro-diversity position. After that, any idea that could be styled as anti-diversity was doomed to fail; this was the sword of invincibility.
At that point, the game became a simple one every child plays: find some way to argue that your opponent is doing the one bad thing. This requires some way of linking their actions with the bad thing, usually through a tenuous chain of arguments. For Leftists, victory came through theories of disparate impact.
Under impact-based theories, anti-diversity thought exists wherever diversity is not working.
You can see how circular this reasoning is. If diversity is not working, it is because Anti-Diversity Satan has made it fail. And, even better, he has done so deliberately, because he is cruel. This allowed the transformation of all who were not pro-diversity into Klansmen and concentration camp guards in the eyes of the public.
At this point, it is clear that diversity has ended the United States. In order to subsidize the vast underclass, it has converted itself into a Soviet-style system of redistribution which has taxed its middle class out of existence, and created enough social problems that most places in most cities above 100,000 are dangerous and only having a lot of money buys you into the nice places.
The real question now is whether conservatives will wake up and stop complaining about specific groups (Muslims, Negroes, Jews) and recognize that all diversity is harmful, and that America must return to its WASP roots much as Europe needs to return to its indigenous cultures. The goal is not complain about these groups, but to assert our own group and our right to exclude all others so we have self-determination and rule by our own culture.
Much as other empires, such as the French and Russians, ended themselves by going down the Leftist path, now the West has followed them, having disregarded the examples of the Greeks and Romans.
Leftism succeeds because it sets up an idea that is socially unacceptable to oppose, which is that everyone must be concluded and all of us must validate each other. That notion appeals to our human desire for control, to keep others from rising above us or getting ahead of us in ability, and it is a force like the gravity that implodes elderly planets.
Since each generation is born anew, it can be resisted, but only by a society that holds true to its cultural values and opposes socializing and social philosophies like Leftism. Such a society might seem plain to our eyes: good basic living, not much excitement, heavy emphasis on morality and strong naturalistic rituals.
And yet, it would not be a suicide cult like the West has become.