Dun’s heart had been excited about reaching unevangelized people since his youth. He served in pastorate of churches in during school. In 1962, he married Harriet Long of Montgomery, AL and served churches in Louisiana and Alabama. In 1971 they resigned a growing and exciting church to go to the foreign mission field. They joined New Tribes Mission, a nondenominational church-planting mission agency.
After completing the specialized training for tribal evangelism in Pennsylvania they were asked to stay on the home staff and help train and send others. They taught in the Mission Institute there for 3 years. In 1974 the Gordys were asked to move to Baker City, OR to help establish a training center for missionaries. Dun then began traveling among churches, Christian schools and colleges throughout the Pacific Northwest and western Canada, recruiting laborers for the tribes and language groups who still had not heard of Jesus.
Dun’s ministry included the establishment and leadership of short-term missions program. He traveled extensively to foreign countries where he had many opportunities to preach the good news as well as teach as visiting professor in Bible colleges and seminaries.
Dun had the privilege of visiting tribal missionary work, some in the most primitive groups on earth. He has traveled in 25 different countries and has had the privilege of preaching the Gospel on every continent – except Antarctica.
In 2001, Harriet suffered a near-fatal heart attack that left her with permanent kidney failure. She lived on hemodialysis treatments until our Lord took her home in 2010.