There's also a difference between civil war and genocide. Lenin and Stalin explicitly murdered millions of their own people via execution or gulags.
No, that's just not a significant argument against communism in general, as similar things happened not just by the "Nazis" but by all major regime changes. Europe had power struggles, civil wars, executions, economy mismanagement etc for 2 centuries leading to the 20th century (which brought WWI and WWII and the colonial wars).
Heck, the modern democratic era started with hundreds of thousands executed in the French Revolution, and then the Napoleonic wars -- and countless other peripheral wars, power struggles, and bloody revolutions.
When Communism came about in Russia, non-communism Europe was torn by the bloodbath of WWI, pogroms, ethnic tensions, etc.
But when it's up to communism we do a sleight of hand, and gather all deaths under communism, in all countries, under various reasons, and do a mass tally to prove how bad it is.
Maybe do a similar tally under non-communism? Let's even constrain it to the 20th century.
Only then would a comparison make sense, whether communism is so worse than our cherished non-communism systems, or whether we're just summing all kinds of 20th century wars, tensions and power struggles that happened to take place under communism in some countries, and forget the similar happenings in non communism countries.
Now on to the ideological murders:
- Gulags
- Political executions and struggle sessions
- Economic-political executions (bourgeoisie, kulaks, petit-bourgeoisie)
- Ideological pseudoscience leading to famines (lysenkoism)
- Ideological drives leading to famines (the great leap forward)
- Military executions for betraying the cause
- The pervasive surveillance for "counter-revolutionaries" leading to people being imprisoned and tortured for curtain-twitchy neighbours
And that's just focussing on the Soviet Union and China. I don't think you could even attempt to argue that the Khymer Rouge were genocidal.
Need I go on? You might think communism sounds nice in theory (I don't, I still think it sounds horrible in theory) but at some point (preferably before you've caused millions of deaths) you should be able to say "actually, it's a nice idea but doesn't work in reality".
To be explicit, the parts that are inherent include purging the "capitalist class", the central planning of the economy (because how else is distribution of goods going to happen? You can't scale local markets to a whole nation that produces advanced goods with long supply chains), the complete rejection of alternative political beliefs and democratic politics, and that's just off the top of my head.
To be explicit, the parts that are inherent include purging the "capitalist class" [...]
Yes, but »purging« has an unnecessary negative connotation, it sounds a bit like just killing everyone.
[...] the central planning of the economy [...]
No, communism and free markets would work together just fine.
[...] the complete rejection of alternative political beliefs [...]
No and yes. Whatever political beliefs you hold, you will usually hold that your believes are more true or better than all others. So this is no more true or false for communism than for any other set of political believes.
[...] the complete rejection of [...] democratic politics [...]
No, why would that be? There are as many things in a communist society as in any other society that require making decisions and that may have competing solutions. Why couldn't you make them with a democratic process? Heck, you could democratically decide to become a communist society and democratically decide to stop being a communist society in case you are not happy with the result.
And even if you deemed communism untouchable and would insist that communism must not be subject to the democratic process, even then a huge number of things like health, foreign, or environmental policies are still independent from your economical system to varying degrees and could still be subject to the democratic process. But that is of course a silly idea.
By the way, note that communism is a heavily overloaded term especially if left unqualified. You can certainly find people that believe communism requires central planing, that communism requires a violent revolution, or any other combination of things. So you could certainly support some if not all of your points by just referring to specific groups with specific sets of believes.
When I refer to communism without qualification then I mean the very essence of it in the sense that it is [almost] universally accepted as an aspect of communism and not specific to some variant or interpretation of communism.