Other significant influences in his early life were Thomas Burke, a Blantyre evangelist, and David Hogg, his Sunday school teacher. At age nineteen, David left the Church of Scotland for a local Congregational church, influenced by preachers like Ralph Wardlaw, who denied predestinarian limitations on salvation. Influenced by revivalistic teachings in the United States, Livingstone entirely accepted the proposition put by Charles Finney, Professor of Theology at Oberlin College, Ohio, that "the Holy Spirit is open to all who ask it". For Livingstone, this meant a release from the fear of eternal damnation. Livingstone's reading of missionary Karl Gützlaff's "Appeal to the Churches of Britain and America on behalf of China" enabled him to persuade his father that medical study could advance religious ends.