Why did people that were against the holocaust let it happen?

It can be seen through the term "silent majority", in which those who were against the Holocaust did not voice their opinions for fear of being oppressed by the Nazi Power, and were not able to stand together against the regime. Many people did not want the Holocaust to happen, but because they did not stand up against it & voice their opinion, it still occurred. Remember, those who know about the situation and stay in the sidelines are as bad as the perpetrators themselves.