You wrote: "The victims of Stalin's purges in the Red Army and the Communist Party were as much advocates of Marxism as he was. They were hardly advocates of freedom."
I never mentioned those people. I was thinking about those who were clearly and irrefutably murdered: common people, not those who worked for Stalin and then were cruely betrayed as they had betrayed others.
"You are arguing technicalities here, unless you really believe that Catholics may justly punish non-Catholics for their beliefs by prison, seizure of property, and even execution as long as it is done by men in judicial or clerical robes. The fact is that, in 16th Century England, two Catholic men were murdered by Protestants and two Protestant men were murdered by Catholics, all under color of law. The state actors in these and other cases did not act in a Christian manner."
The fact is that two Catholics (and many thousands more) were murdered by Protestants, and three hundred Protestants were put to death (but not murdered) according to the law.
"It is true that all ages have barbarities, but the era of the religious wars was particularly so, as was the 20th Century with the Communist and Nazi regimes."
No. The 20th century was more barbaric than the 16th. The 20th was also the step-child of the 16th. As Pius X predicted, Protestantism had inexorably led to atheism.
Stalin had both Marxists who opposed him and non-Marxists (kulaks, religious believers, ethnic minorities) killed. There may have been a degree of poetic justice in the imprisonment and execution of the Marxists, but both groups were persecuted or murdered under color of law. There is no essential difference between the actions of Stalin and those of Queen Mary or Queen Elizabeth I, other than the scale of murder. If the premises for a trial are based on unjust law, then the trial is therefore unjust and those sentenced are murdered.
As to your presumption that Protestantism leads to atheism, history indicates its falsehood. The first major outburst of atheism occurred in the French Revolution, in a nation where the Protestant influence was effectively removed following the revocation of the Edict of Nantes and the emigration of the Huguenots to America and the Protestant nations of Europe. A major seedbed of atheism was Germany, a nation divided between Protestants and Catholics and where the devastation of the Thirty Years War caused many Germans to reject religion altogether. In the late 19th and early 20th Century, regimes in Italy, Mexico, and Spain, where Protestantism never established more than a toehold and where the government and Catholic Church effectively suppressed religious dissent, were extremely anticlerical. The anticlerical parties in those countries were influenced by atheistic, Grand Orient Masonry, based in France, and severely persecuted the Catholic Church and the clergy. As you are probably aware, the unified Italian republic, led by Grand Orient Masons, stole the Papal States and forced several Popes into exile in the Vatican. The first successful Communist revolution was in Russia, a nation historically neither Catholic nor Protestant, but Orthodox. The most powerful foe of Communism during the Cold War era was the United States, a nation mainly founded by Protestants and with a Protestant majority (at least until recently).