Our conscience helps people know what actions are right or wrong. Even in the case of the Holocaust, many Germans chose to follow and murder innocent people despite knowing it was wrong. They involved themselves with the mass murder of German Jews. Although some people were not directly involved with killing the Jews, they freely chose to discriminate and harm them. Their choice to mistreat the Jews despite the obvious unethical implications should not be forgiven. Studies show that when people are under another authority, they feel less responsibility for their actions. Although this partially explains why Nazis may have followed authority so easily, it does not excuse their actions. The Holocaust would not have been possible without the enormous amount of support from all the soldiers that followed orders without considering their conscience. Therefore, those involved in the Holocaust should not be forgiven.
During the criminal trials following the Holocaust, many Nazis claim that they were unaware of the mass murder of the Jews. Some soldiers were responsible for the deportations, but they had no idea about the ultimate fate of the Jews to concentration and extermination camps. In the trials, documents were brought forth, showing that while the Nazis followed deportation orders, they were unaware that they were going to be killed. 
[P1] Every human being has a conscience. [P2] A conscience tells a person what is right and wrong. [P3] Nazis freely chose to do wrong despite their conscience. [P4] Therefore, the Holocaust cannot be forgiven.