Christian faith, Shia Islam and Nazi Fascism share one common in their roots: All three ideologies or religions are based on the myth that their founder (or at least one of their earliest believers) were killed by the enemy. Hence, all three seek for supporters who are willing to take revenge by assasinating as many as possible of the branded enemies. Orthodox christians still claim today that Jesus was killed by the Jews, and this was used as justification for pogroms against the jewish minority over centuries. For the german nazis, the death of Horst Wessel, a pimp who recruited SA thugs in gang fight and who was shot by a communists in a privat dispute was their big founding mythology. They used this story, after adding a completely made-up political component to it, to arrest, torture and kill hundred thousands of communists in the death camps auf Dachau, Buchenwald, Sachsenhausen and Bergen-Belsen. The third ideology in this group, Shia Islam is based on the mythology that Hussein ibn Ali, grandson of Muhammad and funder of their faith lost his life in a military battle against the Umayyad Caliphs in Kufa. According to Shia faith, Hussein died as a martyr. During the annual Ashura the shiits mourning Hussein by torturing themself, whipping iron chains over their back and riping the skin of their breast and head until blood spreads all around. The violence, however, is not restricted to themself: Foreigners or any non-Shia believers are recommended to stay away from the Ashura procession, since attacks against such "Kufr" (or non-believers) are considered a normal emotional outburst of Shia islamic faith. It is also not surprising, that during the late-November 2011 attacks against the British embassy in Tehran the thugs shouted slogangs condeming all enemies of Shia islam and praising the memory of Hussein.
In all three cases, Christian faith, Nazi Fascism and Shia Islam, the believers are convinced that the death of one of their legendary funders, either killed in a military battle, sentenced to death by a court or shot dead in a gang fight, was a loss so sever that a virtually unlimitted number of the "enemies" has to be killed in revenge. Hence, an ever-lasting physical aggression against the Kafrs, the pagans, heretics or the political opponents is the conditio-sine-qua-non of religions and political ideologies who are based on a martyr founding myth.
This does not exclude other faiths or ideologies to behave aggressive from time to time. But as a natural self-protection there is always a tendency to settle an aggression. For sure, Israel is not a pacifist nation, nobody will honoustly claim that in the long-lasting tension between the jewish nation and its arab neighbours the israel army acts like a peace keeper. The difference between the jewish religion and Shia Islam or medieval Christianity is that the thora clearly says "Eye by eye, tooth by tooth" (עין תּחת עין : ajin tachat ajin). It warns everybody to continue an aggression, after a criminal act has been settled by an appropriate punishment. Even the Mafia, notorious for aggresive acts of revenge against its enemies, has a certain ethic by finishing a dispute ones the "law of crime and punishment" has been settled. As compared to ideologies that are based on the mythology of an eternal burden of sin (Jews are still considered by the catholic church as murders of Jesus and should be stung with remorse), the concept of Nemesis in greek philosophy was revolutionary by stating that when an offender was righteously punished, its crime should be considered as settled and no further aggression against himself, his family, his nation or religion is justified.
Neither Shia Islam nor Nazi ideology or Christian religion have this concept of nemesis. Aggression against all Kafr is immanent at Ashura feast. And how indifferent right-wing and nazi-supporters are in killing innocent people whom they consider un-worthy became obvious not only after the Norwegian Breivik mass-murder, but nowadays in Germany when the systematic assasination of foreigners by a self-declared "national-socialistic underground" organisation is revealed.
And christian religion ? Sure, they more or less successfully try now to hide the historical importance of their own martyre mythology. Now they like to make people believe that christianity was always synonymous with tolerance and pacifism. But in fact, for at least 17hundred of their highly praises 2000 years history, christianity reproduced the idea of Jesus being the victim of the evil Jews as a strong argument to gather their supporters and promote the worst crimes during the crusades.