Actually the people who stood up to Hitler generally got murdered afterwards. You cant sya they were dull minded the german people saw Hitler in the beginning as there saviour. Germany was in tumoil because of the economic depression and the effects of the Treaty of Versailles, they had gone from a Kaiser to a democracy within a year. Hitler promised to bring Germany back to the powerful stsate it once was. If you were a German citizen wouldnt you vote him in when he promised to put food on your plate (many German people were starving).
You just have to remeber that its not people being dull minded you have to think about the situitions of the time. These german people were so despereate that when Hitler promised to help Germany that they voted him in thinking he would help. This is when Hitler showed his true colours when he brought in the Enabling Act which gave him full dictorial power.
You have to remeber that the people who asked questions got killed, the people that stood up to him got killed.
The Holocoust is very sad and should have never happened but you have to understand why it happened.