Communism has a shared ideology leading to mass deaths. This ideology (radical egalitarianism in opposition to property rights) seems to be shared among all leftists but not rightists. The ideology is central to many of the mass deaths (eg Holodomor).

Is there some shared ideology (or even mere idea) which is shared among Hitler, the Shinto Japanese, the Russian Tsar and the Pakistani military dictatorship? Is it an idea that leftists do not share?