Here is one of many articles that can be found about religious resistance to progress that would greatly and obviously reduce suffering. For those who don't care to click, it is about religious opposition in the 1840s to the introduction of anesthesia in surgery.
It is astounding to think about getting a limb amputated, or even teeth pulled without anesthesia, and yet I guess it used to happen quite frequently. Religious opposition to this sort of thing is definitely a pattern rather than an isolated event, though. Religious voices spoke against the introduction of a smallpox vaccine in the 1700s, claiming that to interfere with smallpox would be to interfere with god's plan. Even today, I have had multiple friends who claimed that disasters such as tsunamis in Asia were meant to happen as part of god's plan and that those people must have deserved it somehow.
I'm really not sure exactly how these sort of people go about their lives thinking they are living according to god's plan when it seems that they believe any act of apparent free will is to interfere. But that's beside the point I guess.
I really have no idea how I would even want to live through having, say, my leg cut off at the thigh without anesthetic. This is where religion must come in. "Mind over matter" is definitely a real thing. If you believe something strongly enough, it will have effects on how you perceive. I suppose, then, that people believed in religion back in the day because, well, they kind of had to. Life was too ugly to live through without it. I definitely wouldn't be able to tolerate it myself.
Another coping mechanism often coupled with religion seems to be thinking that pain is good for you and necessary for happiness. To not think that would be to admit the unbearable idea that pain is meaningless and undeserved, and life is unfair--some people live less painful lives than others.
Which is all to say, I guess it is kind of understandable that people would resist advances that will obviously make this deeply flawed world better, but we need to start letting go of that resistance. I think it will be easier as there is less to cope with still in the future. The less we suffer, the less we need god. Kind of makes sense, really, considering the zeal that used to exist in the world compared to the lukewarm nature of today's religious. Sure, plenty of people still claim to be religious in the 21st century, but how important to them is it really? I would argue that it is far less important than it used to be.