Woodberry: 9/11 led to an increase in the number of missionaries to Muslims
One of the positive effects of 9/11 was that it forced Christians to seriously consider Islam and how they should respond to its growing global presence and authority:
The most significant missions development since 9/11 has been the increased number of students who want to be missionaries to Muslims. The first class I taught on Islam after 9/11 had 100 more students than usual. This interest built on the emphasis of the "AD2000 and Beyond" and Lausanne movements on the "10/40 window," the section of the world that includes major non-Christian religions. Increases in student numbers were also the result of interest in Muslims raised by the 1979 Khomeini Revolution in Iran. Todd Johnson, an editor of the Atlas of Global Christianity, has calculated a 26 percent increase between 2005 and 2010 in the number of missionaries working in Muslim-majority countries.
From Dudley Woodberry's article at Christianity Today, read the whole thing HERE.