@keobooks’ answer is probably pretty spot on. I would add:
1) What people knew. There is some debate over what exactly the general population did know, and how much deniability or disbelief or suspension of disbelief (DDSD – don’t know what to call it really; see #3) the public might have plausibly been conjured. I personally have trouble believing the general public didn’t at least have some inkling about the brutality, if not the extent, and there are photos of Germans being marched through death or at least concentration camps, especially in the east.
2) Politics
2a) More effective political coalitions after Bismarck were able to win power by uniting the conservatives and the more right-wing liberals with Catholic-dominated Center Party – until Hitler. People like to say Hitler didn’t win an election, which is arguably true, but the uncomfortable truth is the National Socialists and another right-wing nationalist German National People’s Party (DNVP) together won a majority at least in 1933. The NSDAP + DNVP vote was one of those rare times when the Center Party was unnecessary to form a functional government in Germany.
Modern politics hook: the Christian Democratic Union that emerged after the war has arguably been closest to a dominant party in Germany since. Its ideology probably resembles the Center Party most accurately, but it has a broader appeal.
2b) The trade union-dominated “moderate left” elements broke up, favoring either Stalinists or the Nazis themselves. The other “moderate left” faction, so-called left-liberals, who were probably akin ideologically to the type of socially permissive urban yuppie who voted for John Kerry, were probably by themselves too small to matter much at the end of the Weimar.
In the case of the left-liberals, “left” should probably be taken to mean “civil libertarian” and “not nationalist.” Economically, they were relatively right-wing, at least by today’s standards. I think it’s fair to say these factions re-emerged as the modern German Social Democratic Party.
3) Conditioning. It goes without saying the Third Reich’s atrocities happened against the backdrop of confusion, war, obfuscation, propaganda, and even other regimes’ (mainly Stalin’s) atrocities. There is a geographic reason for the DDSD above. The epicenter of the holocaust’s death machinery was more in eastern Germany, now lost territories (not the later state of East Germany, but Germans from now lost eastern territories, mainly Prussia). Many eastern Germans who were closest to it were closer to the more brutal eastern front and then were themselves victims of mass expulsion to the west a few years later, and I think there is still a lot of unspoken displeasure about that even today. I really wouldn’t be surprised if people from the east knew more than people from the west because of better front row seating, but people from the east might also have significantly more trauma related to what was going on.
4) Aftermath. Unfortunately few people asked this question in 1935. A significant population ended up in the postwar German Democratic Republic (East Germany) where the severe RWA conditioning continued for several more decades. Between the trauma of the Depression, the war, the postwar partitioning, and finally the uncertainty of the Cold War, what survived of the German population as a whole probably had trouble reflecting on Third Reich until the 1990s – I imagine most of the people posting here remember that decade.
@Coloma: my German family used to say Americans had more civil courage than Germans. Hard to imagine someone saying that after 9/11 though. :-\