Popper had been a Communist in his youth but became disenchanted. He became a defender of the liberal order. Liberal in the broadest sense of the word, independent judiciary, rule of law, that sort of stuff.

Life is shit.

Arguably true to the extent such people were given the chance to try to implement their paradise.

You inherently can't have both sustainable paradise and personal freedom.

True if you zoom out and take the global historical picture. But zoom in on Martin Luther King and you find a religiously motivated person doing good. I have a dream promises a kind of heaven on earth.
I can still be atheist and see good in religious people.

Utopias are unworkable. It's usually one person's vision (or maybe a small group) and they end up forcing everyone into their view. Either that, or it turns into anarchy. Communism is an example of a promised paradise that turned into a hell.