This is literally what he sent me:
You're offspring will reap the demise off your ignorance, be it slavery or another form of retribution. You're unwillingness to acknowledge injustice will bring the wrath of vengeful and irrational beings, seeking reparations in blood. I sought to enlighten you to a reality you were not privy to through the stories of people who lived those hardships. Those "criminals", as you call them, will come to eternally rob you and your next of kin of light... I wish the best for you.
Really fucked up stuff, this was a good friend of mine. What happened to people?
This is clearly a death threat not just to you but also to your kids. Report him to the police. Death threats to children are no go. Then report his employer and all future employers with the police report. Report this to your kids school. Report this to his kids school. Report this to your neighbors. Report this to literally everyone.
I'm not a commie. I should though, but I probably won't report him.
You really should. As some point the right will have to start using the left’s tactics against them.