Children Of The Tribulation was the name of a school in Israel that Buck and Chloe Williams had opened at the beginning of the Millennial Kingdom, in order to help children become believers in Christ before their 100th birthday. Their son Kenny was one of their students before he became a worker in the school. Chloe's brother Raymie also worked at the school along with Abdullah Smith's two children Zaki and Bahira, all three of which were raptured as children and returned in the glorified bodies of adults.
While the school was in operation, they had Biblical figures such as Noah, Joshua, Caleb, and King David visit the children to tell their stories. Qasim Marid, who was a friend of Zaki, worked at that school for a time, but was actually an infiltrator from The Other Light sent to cause trouble, even among the inner group of Christian believers called the Millennium Force, framing Kenny for his being a defector to The Other Light. When the truth was revealed, Qasim was fired from his job at the school before his death.
Kenny and Ekaterina Risto, who fell in love and married each other, formed a branch of this school in Greece and operated it until they were both too old to handle things. In fact, by the end of the Millennial Kingdom, the school was mostly run by glorifieds as the naturals saw the ravages of time catching up with them. The school was eventually dissolved by the end of the Millennium when Jesus Christ cast Satan into the Lake of Fire and ushered in the "new heavens and new earth" after the Great White Throne judgment.