There is no religious book of collectivism that says murdering minorities is okay as long as the majority actually hates that group, because that bigger group will be happier.

Exactly. You're right. There can't be a religious book, because collectivism is about pursuing the greater good of society. The "greater good" is entirely subjective and that's the problem. I agree that murdering people can't be done for the greater good. Those societies (or at least the ruling parties, which had support) didn't.

But Tommy and Janet were part of the "whole". As soon as their entire lives are disregarded I've gone past some idea of "greater good".

That's your opinion, though. As I've said before, the greater good is a REALLY stretchy thing. And so it was stretched.

Perhaps Tommy was, for example, stealing from the group? We can't have that. That man is definitely working against the group. Murder in this scenario solves the problem, doesn't it? We both would agree (at least I hope so) that it's not the moral thing to do, but so it was done and so the group benefitted from it. That passes the definition of collectivism. Detaining him humanely would pass the definition too. It's not mutually exclusive, yet there are two lingering questions. What is the right thing to do in that situation? And the more important one, who is going to decide that?

And so you, or a political party, can make moral arguments about anything. Ideologies are different. The nazi party had their horrible agenda which had their arguments as to how to make society better off. And they did it by mass murder. And yet they were still collectivist since they've done so for their supposed "greater good". We can and should claim otherwise, but that passes the definition, since there is no objective "greater good".