Born in Albuquerque, New Mexico, Armerding was the son of an itinerant preacher and grew up in a variety of places in the Southwest U.S. His high school graduation in San Diego, California was in 1935.
For two years after his high school graduation, he lived in Wellington, New Zealand, working on a farm.
Armerding earned an undergraduate degree in history from Wheaton in 1941, where he was a classmate and good friend of Billy Graham (who had transferred in to Wheaton from Bob Jones University via the Florida Bible Institute), and received a master's degree in international affairs from Clark University in 1942.
In World War II, Armerding served as a line officer in the Pacific Ocean aboard the heavy cruiser USS Wichita, which participated in 11 naval engagements, including the invasion of Okinawa.
In 2007, he was moved to Windsor Park Manor in Carol Stream, Illinois, where he battled with dementia until his death (in his home) in 2009.