Ronald J. Sider (1939-2022) was a theologian and social activist who founded Evangelicals for Social Action (now Christians for Social Action), a think-tank that seeks to develop biblical solutions to social and economic problems. He published over thirty books, including the landmark Rich Christians in an Age of Hunger, and wrote hundreds of articles in both religious and secular magazines.

Sider received a BA in European history from the University of Waterloo in Ontario and a Master of Divinity and PhD in history from Yale University. He was an ordained minister in both the Mennonite and Brethren of Christ denominations, but focused on a long teaching career. He served as professor of theology, holistic ministry, and public policy at Palmer Theological Seminary in Wynnewood, Pennsylvania, and as a founding board member of the National Religious Partnership for the Environment.

Read tributes to his life and ministry in The New York Times and Christianity Today.