It was Vietnam which really turned the tide,” writes Anne C. Loveland, author of the only book-length study of the evangelical wave within the armed forces, American Evangelicals and the U.S. Military, 1942–1993. Until the Vietnam War, it was the traditionally moderate mainline Protestant denominations (Methodists, Presbyterians, Episcopalians), together with the Catholic Church, that dominated the religious life of the military. But as leading clergymen in these denominations spoke out against the war, evangelicals who saw the struggle in Vietnam as God’s work rushed in. In 1967, the Assemblies of God, the biggest Pentecostal denomination in the world, formally dropped its long-standing commitment to pacifism, embracing worldly war as a counterpart to spiritual struggle. Other fundamentalists took from Vietnam the lessons of guerrilla combat and applied them to the spiritual fight through a tactic they called infiltration, filling the ranks of secular institutions with undercover missionaries.
“Evangelicals looked at the military and said, ‘This is a mission field,’” explains Captain MeLinda Morton, a Lutheran pastor and former missile-launch commander who until 2005 was a staff chaplain at the Air Force Academy and has since studied and written about the chaplaincy. “They wanted to send their missionaries to the military, and for the military itself to become missionaries to the world.”