Communism's atrocities are only possible with a strong, centralized government. Which is why I stress the importance of decentralization, of undermining government power, and of stressing the rights enumerated in the first ten amendments to the US Constitution. A popular -- and serious -- error is imagining that somehow the Bill of Rights was a gift of the central government. Those rights are not: they were essentially forced on the US federal government as a cost of ratifying the Constitution by the necessary number of states, and they are there to undercut government power, and to tie the hands of the government. Without centralized government, there can be no genocide, because the potential victims will leave when they can. This doesn't mean there won't be individual deaths, but the horrific numbers in the 20th century cannot occur without centralized power.
Whenever we want to strengthen government power because we imagine that we agree with whoever is currently in power, we should remember 2 things. The first is that Rom. 3.23 is still true, and all are sinners, and given the ability, all of us can do horrific things. The second is that the wheel of history turns, and those we disagree with may one day be in power. With a weak government, the marginal people who always go into government employment (cf. Judges 9.7-15) will imagine vain things, but they will essentially be unable to carry them out.
In this video, Dith Pran speaks about the murdering Khmer Rouge in Cambodia: