While the 10/40 paradigm refers to a geographical area, the 4/14 Window concerns itself with children and youth between the ages of four and 14 who are growing up outside of the church.
"There is a recognition that we are losing the children of the world spiritually," Bush told The Christian Post on Tuesday, the last day of the Transform World Conference on the 4/14 Window in New York.
Statistics show high percentages of teens and young adults ages 15 to 24 are departing from the Christian values they were raised with, he said.
"So this becomes a very critical moment to aim lower at the 4 to 14 [age] as the beginning place and come back to there with significant concentration," contended the mission strategist.
Bush noted that the decade represented by the 4/14 Window is the most critical period in terms of human development. During these years, the perspectives of children are profoundly shaped – either positively or negatively.
Mission strategies developed for the 4/14 Window would be implemented by parents, pastors and other role model figures who play key roles in shaping a child's worldview.
The new vision, Bush said, is "raising up" a generation that will be "agents of transformation" that God will use in the various spheres of society.
"God is calling us to radically change the way we view children and to respond to their strategic importance and rightful place in His Kingdom," states the brochure for the 4/14 Window global summit.
While Bush is calling on Christian leaders to focus on the 4/14 Window, the Argentina-born missiologist stresses that the 10/40 Window is no less important now. For Bush, the highest priority is the 4/14 Window within the 10/40 Window.
More than 350 people from 70 countries attended the global summit in Flushing, New York this week, titled "Raising Up a New Generation from the 4/14 Window to Transform the World".
During the three-day conference, Christian leaders from around the world committed to prioritising the mission to reach, equip and empower the 4/14 generation to maximise their transformational impact while they are young, and continue to impact the world for Christ for the rest of their lives.
On Monday, Christian leaders launched the 4/14 Initiative at 5:30 am during a morning prayer meeting. More than 1,000 people – conference delegates and members of Promise Church, where the event was taking place – took part in the morning gathering.
Since its first gathering in 2005, the Transform World movement has spread to five continents with national gatherings taking place in India, Korea, Singapore, the Philippines, Malaysia, Burundi, Africa, and across Latin America.
Its most recent meeting was hosted in partnership with Promise Ministries International.