After earning a PhD in Church History, David taught at Bob Jones University Seminary for nearly forty years. In addition to writing books, he has taught in churches, colleges, and seminaries. His hobbies have included researching and photographing historical sites, including America, Europe, and the Middle East. For many years, David conducted tours to the British Isles and Holland, then the Middle East tracing the Seven Churches of the Book of Revelation, the Journeys of Paul, etc. He loves to collect and read historical and theological books.