Agreed.
I'd somehow like to broaden it to something more general to encompass the entire international Left instead of only the Bolshevik revolution but, if we narrow it to just one single event, that one can fairly be represented as the most tragic in many centuries.
Correct, it was more than that even (Bela Kun in Hungary and the commies in Germany and in China and in....everwhere. Even here). Getting back to the Church. I'm as far theologically as one can be from Catholicism (I'm Unitarian). But the Church does a heck of a lot of good. There is no international organization of its size which is standing up to the likes of George Soros, Maurice Strong, Ted Turner, the UN and hundreds of socialist NGOs. The current Pope helped bring down the evil empire. Pope Leo XIII warned where socialist were going 35 years before Lenin and Trotsky gained power and started killing.
I much prefer people be involved in their church than look to the state for all answers. Everyone who desires liberty loses if the Catholic church is weakened.