In her latest long-form feature, Sarah Eekhoff Zylstra tells the extraordinary story of how the 75-year-old retiree and former missionary Rosemary Jensen and the former Gordon-Conwell Seminary professor David Wells created a special Bible study for African children and their parents.

As Zylstra says, “The curriculum was written by Reformed theologians and is used—partially or completely—in orphanages, church schools, widows’ groups, and partner churches in Africa. Thousands of students, teachers, employees, church leaders, and church members have studied the Bible with it.”

Children in 10 schools run by the Rafiki Foundation spend more than 10 years in the Bible study, and cover 90 percent of the Bible verse-by-verse. A Bible study this intense “doesn’t exist anywhere else—even in the United States,” says Wells.

This month, though, the Rafiki Bible Study for Groups is coming to America. Are you ready for this 553-week challenge?