The Taliban executed two of the Korean hostages because the missionaries would not convert to Islam.
The world is still a dangerous place for those who feel compelled to spread Christianity like the missionaries of old. But one part of the world is the most dangerous yet most "fertile" zone for Christian missionaries. That zone is known as the 10/40 Window.
Comprising ten degrees north to forty degrees north in the Eastern Hemisphere, the 10/40 Window contains three Christian majority countries (Portugal, Greece, Philippines), and a few mixed regions like South Korean South Sudan, Ethiopia, Nagaland. However, the vast majority of the region is Muslim, pagan, or official atheist.
Other factors like 84% lowest quality of life, 82% of the worlds poor, etc create a base population with qualms towards the establishment. Evangelical groups hope to convert many of these inhabitants and see the situation as an opportunity.
However, history has been rough towards Christianity in the window. Nestorians came close to converting Persia and China but they were crushed. Islam destroyed the Christian Middle East and any chance to spread east, and the Jesuits ran until government persecution in efforts to convert China and Japan. Today a militant strand of Islam is actively fighting missionary efforts.