en.m.wikipedia.org/wiki/2007_South_Korean_hostage_crisis_in_Afghanistan
Koreans have a bad reputation in middle east for sending too much christian missionaries there..
That's true, and I remember the controversy in Korea about the government allegedly paying ransom to get the missionaries out, even though the same government had warned them numerous times against going to Afghanistan.
That said, I don't get the impression that resentment against Korean missionaries really translates into murderous hatred of the Korean government. While I do think that the "blowback" hypothesis is somewhat overstated, in order to get Islamist terrorist attacks against your country, it does seem to help to have a significant military presence in Muslim countries, and/or a history of colonizing Muslim countries. Korea does have a slight bit of the former, in Afghanistan, and while it did play some role in motivating the kidnapping of the missionaries, it doesn't really seem to have put Seoul on anyone's radar as the Evil Empire; and of course they have no history of colonizing Muslims.