The concept of hell is fairly medieval?
No. They just took the idea and ran with it. Embellished it massively for all sorts of nefarious reasons, but it wasn't their concept or invention.
We have Jesus himself to thank for that. He was pretty clear about what would happen if we didn't toe the line. Not quite sure why so many Christians disregard 99% of what he actually said. It wasn't all about loving each other, you know.
I think it might be because most don't actually know what he said...their vicars don't bother to read out the controversial bits on Sundays.
And yes, lots of Christians do believe that evolution was the mechanism God set up to create life.
Problem is, when you actually understand what evolution is all about then it becomes clear that lots of the things Christians hold dear...that we are special, made in his image, that he's omniscient...all falls apart. Evolution disproves those things.
An omniscient, universe creating God is entirely at odds with the level of randomness evolution needs.
Of course, nothing can truly disprove the existence of the Christian god - but an understanding of evolution comes very close.