Because it flies in the face of their 'this earth was put here for man's use' doctrine. Also, it requires change from the standard American consumptive lifestyle Kristians subscribe to. It's the way we've always done it, American way..blah blah. In general, bringers of bad news are maligned by the angry hairless monkeys on the receiving end. And finally, you couldn't find a less analytical, scientifically minded group, given their beliefs. All science is an affront to their bible, from evolution to genetically based man on man action. No amount of evidence will convince many of these folks of anything.
Hopefully, a sterilizing virus that selects for stupid will come along...