Who said it was stupid? Evangelicalism is one of the fastest growing Christian denominations AFAIK, so arguably it is a quite successful belief. Of course it is unscientific, but that is a different issue. It might be smart to deny science depending on what you want to achieve.
I don't know much about religion in South Korea, but I would assume that the denialism is due to American influence, since it seems to be a recent phenomenon (according to the article). Jehovas Witnesses is another world-wide movement that denies evolution, and it also originated in the US.
Calling it fairy tales is never, ever going to get that side of the argument to converse in any manner better than defense. Engagement would be better. Some very, very smart people believe exactly the way you wish they wouldn't.
Unfortunately, basing your worldview on unprovable and self-referential axioms like "the Bible is the word of God because it says in it that it is the word of God" and "the Bible is literal truth because it's the word of God" makes it hard for people who base their worldview on scientifically derived axioms to debate with you effectively. If you can't agree on the foundational axioms, then debate on higher order results of those is usually pointless. I think that's the crux of the impasse there. I'm not sure if I've ever seen someone change their fundamental beliefs, probably because it would involve refactoring everything, and that's a ton of work.
I say it is stupid, because I think it is stupid. And it doesn't matter if there are loads of people out there who believe in it, or if their numbers are growing, I still think it is stupid. The available quantity of cult followers doesn't really faze me on this, that just means there's an unfortunately large volume of stupid, and it might need keeping an eye on, in case it overflows and makes a horrible mess.
I don't know much about religion in South Korea, but I would assume that the denialism is due to American influence, since it seems to be a recent phenomenon (according to the article). Jehovas Witnesses is another world-wide movement that denies evolution, and it also originated in the US.