On June 28, 1987, four Dallas-based Christian leaders were killed in an airplane crash as they were returning from a Focus on the Family retreat in Montana: George L. Clark, chairman of the board and CEO of MBank; Dr. Trevor E. Mabery, a surgeon who helped found Humana Hospital-Medical City; Hugo W. Schoelkopf III, an entrepreneur and sporting goods manufacturer; and Creath Davis, founder and director of Christian Concern Foundation. Among the losses...