Book excerpt: Essential. Critical. Revolutionary. Be prepared for Christian missions strategist Luis Bush to change the way you think about missions forever. Twenty years ago, Bush introduced the concept of the 10/40 Window (an area between 10 degrees and 40 degrees latitude where the gospel is least present) and radically altered the landscape of missions. Now, Bush is urging Christians to reprioritize and redirect their energies at the youth of nations. A great opportunity exists to develop and mobilize a new generation of Christ followers, especially those between the ages of 4 to 14; This is the 4/14 Window.