To them, their ends justify any means.

Yes, exactly. Their ideology specifies such a utopian ending that any evils they need to commit now are justified by the Glorious Future that they are ushering in.

I'm not sure of any way you could think like this and not become an utterly immoral person.

If you're of this ideology and you realise that you can hurry things along by kicking puppies, then you've got two options:

• Go and kick as many puppies as you can find - because this results in the Glorious Future, it's perfectly acceptable
• Don't kick puppies. Your moment of squeamishness here delays the Glorious Future and that is - if you're a fully-paid-up cult member - significantly worse than any amount of puppy-kicking you might have done.

That's why these people are awful people.

To them, their ends justify any means.

Yes, exactly. Their ideology specifies such a utopian ending that any evils they need to commit now are justified by the Glorious Future that they are ushering in.

I'm not sure of any way you could think like this and not become an utterly immoral person.