As the 1930s approached, a growing proportion of missionaries going overseas were supported by faith mission boards. Reasons for this have been suggested by conservative missions historian Harold Lindsell: "Liberalism has never been noted for its missionary zeal. The inroads of scientist, behaviorism, and humanism may well have been the consequence of an uncertain theological note which carried no impelling conviction of the Gospel imperative for those without Christ." The theology of the faith missions, on the other hand, has had a compelling motivation for missions, asserting that no person can be saved from eternal damnation except through hearing and believing the Gospel of Jesus Christ.