They describe how they believe firmly how nature works,
Yeah, we know some parts. There's still plenty to figure out though. There's a firm belief that evolution happened, but some of the mechanics are still mysterious. And we still don't yet have a C++ to DNA bytecode compiler.
maybe express amazement and awe at its processes (with no real need to),
Well from an engineering perspective of "let's make a self replicating, learning machine that will contend with other such machines in a eon-long battle royale", yeah, it is pretty neat. Very slow though. And I think one of the biggest struggles that the theory of evolution has faced is the sheer disbelief that such a process could create all the variety and usefulness we see in life around us.
and when pressed to answer whether that's a good way of organising human societies, they (well, all people really) suddenly think its repulsive and stress that "we are equal".
How can belief in natural selection not end up in prescribing it for humans?
Oh, easy. A lot of people were stupid and got some really bad ideas from the idea of evolution. Some really took the phrase "survival of the strongest" to heart. As in, "durr I have more muscle mass then you, I'mmagonna get da girl". But it's not the strong that survive, it's the "fittest". What constitutes fitness? A whole lot of things, from not eating too much, to fitting in to small places, to having an agressive behaviour, to having a passive behavior, to having sharp claws, to having dull claws for digging. If it helps, it makes you fit. And that can mean opposite things at different times.
Some people also think that "selection" is just a euphemism for killing off people. That also isn't true. Selecting who passes on their genes, you know, giggity, is the big step. Surviving to that stage is kind of a pre-requisite though.
And then there's that eugenics thing, which really didn't have any legs to stand on and caused a lot more trouble then any supposed benefit there was.
But humans are a social creature. If it's good for my neighbor, then it's good for me, even on a evolutionary scale.
So the misapplication of this idea has lead to some stupid people doing stupid things. And there's no need to encourage that. That's why you'll see a lot of "evolutionists" fight back against ideas about taking control of our genetic future. Come on, you asked this quesiton when Eud said he wasn't going to have kids. There's nothing really wrong with that.
And lastely, we ARE being subjugated to natural selection. I choose my wife based on certain criteria. We're thinking about kids. There's selection for you. Humanity has changed the game a little, but the game is still going on. Cats, for example, are ruled by selection of the cutest. This is still a form of natural selection, even if it's widely different then before. Another example is the latest fashion for selecting mates has done a 180 and now we like skinny girls. That wasn't always so. I think that happened some time around 1850's right? Anyway, that's a piddly amount of time for there to be evolutionary forces shaping our genes. Barely 15 generations. And there's more then enough outbreeding to keep the race stable.