I think everyone agrees that communists are ‘extremist’ (or perhaps ‘radical’ is what they’d rather call themselves).

On the issue of evil, there are many types of communists. Part of the reason that communists killed more people than Nazis is that there were a lot more communists and they held power for longer. But even there, the group of communists responsible for most of the killings were ‘Stalinists’ (Stalin, Mao, North Korea, etc). There were also many anti-stalinist communists. Some of them came after Stalin, like Gorbachev. But there were also many pre-Stalanist schisms among communists. If I recall properly, Trotsky oppossed Stalin, the menshaviks opposed the bolsheviks (Marxist-Leninists), and the anarchists opposed the Marxists.

Holding all communists responsible for Stalin’s crimes is like holding all Christians responsible for the Spanish Inquisition.