A large part of the why question is rooted in your own observations, most notably one that isn't quite right:
Evolution is not simply a biological mechanism. Humans are creatures of myth and story; we see greater meaning in things. While it's true that the science of evolution simply is what it is, the meaningfulness humans derive from it can hardly be simplified to a "biological mechanism." Biological evolution teaches particular lessons about the nature of humanity and its relationship with the rest of the biosphere, if not the cosmos. Those are really, big, meaty questions that are among the essentials that religions of the world address. The mythos that comes out of biological evolution conflicts with the mythos of prevailing stories of Western culture. It directly threatens the meaningful stories people tell themselves about humans being a special apex with dominion over the earth. So does ecology, honestly, and I wager the anti-evolutionists don't throw the same fuss about ecology only because they are so ignorant about it that they don't know it poses the same threats to their worldview.
There is no putting the matter to rest, that I can see. Not unless you kill the stories, and I do not see that happening. Humans are always telling stories and myth-making, seeing meaningfulness and life lessons in things. There will always be competing stories, and people who think their story is better than someone else's story. There will be people who want to ruin someone else's story. Maybe the best way to put the matter "to rest" is to listen to each other's stories and celebrate them all - value the diversity and embrace pluralism?
