Miller was raised on a large ranch in western South Dakota. He felt an early call to ministry and attended Central Bible College in Springfield, Missouri, where he met his wife, Darla.
At a young age, he came to understand that his ministry would be expressed as a higher education professional and he completed a bachelor of arts in Theology at Oral Roberts University and a master of arts in History at the University of Tulsa.
Miller later earned a Ph.D. in Church History from Boston University and received a grant for dissertation research in East Germany in 1990-1991. He lived in Germany with his young family during the immediate post-Wall era and during German reunification. He then taught at Valley Forge Christian College before coming to Malone in the fall of 2000.
At the time of his presidential appointment, Greg Miller had completed 22 years of service at Malone, serving in the roles of professor of history, department chair for History, Philosophy, and Social Sciences (HPSS), director of general education, associate provost, and provost.
Miller is a two-time recipient of the Malone University annual Distinguished Faculty Award for Teaching, and has also received Malone's Distinguished Faculty Award for Scholarship. He is also a recipient of the Ohio Magazine Excellence in Education Award.
Miller is an ordained minister in the Evangelical Friends Church and frequently serves as a guest speaker and preacher at churches across the region. He has experience as a youth pastor, associate pastor, and interim lead pastor, and served as an adjunct faculty member for Asia Pacific Theological Seminary in Baguio City, Philippines. He has been a longtime participant in Christian, Jewish, and Muslim interfaith dialogue in Northeast Ohio and beyond, and has authored or co-authored more than 40 articles and books on the history of Christianity and Christian-Islamic relations.
An enthusiastic long-distance runner, Miller was a South Dakota State High School 1600 Champion and former Class A state record holder. He coached men’s and women’s cross country at VFCC for seven seasons and has participated in dozens of races, including the Boston Marathon, the Leadville 100, and the North Coast 24-hour. Several times, he placed in the top ten USATF National Ultra Running Championship and is a two-time National USATF Champion in the 100k for his age group. Miller is the current record holder for the four 100-mile summer race series, the Midwest Grand Slam of Ultra Running.
In 2022, Miller and his wife Darla celebrated 40 years of marriage. They have three sons, Alex '11 (Kristin '11), Jeff (Angela), and Jonathan, and a new grandson Owen James.
They reside in the City of Canton’s Ridgewood neighborhood.