Today a group of Calvin Seminary students enjoyed a lunchtime talk by Dr. John H. Armstrong, founder of ACT 3 and adjunct professor of evangelism at Wheaton College, “Missional-Ecumenism: The Protestant Challenge and Opportunity.” Dr. Armstrong spoke about his book, Your Church is Too Small: Why Unity in Christ’s Mission Is Vital to the Future of the Church, where he lays out his vision for missional-ecumenism. Rather than emphasizing the institutional and international focus of the older mainline ecumenical movement, Dr. Armstrong’s vision is focused on local and practical work that Christians of all stripes can do together. It is what happens when ecumenism meets subsidiarity.

The Acton Institute co-sponsored the luncheon along with ACT 3, and it was a pleasure to hear Dr. Armstrong’s story and about his engagement with Christians from a variety of different denominational and confessional traditions. One of the important points he made was the formative influence that Roman Catholic Social Teaching has had on his ethical thinking as a Protestant. He pointed especially to Rerum Novarum and the subsequent social encyclicals as important sources for Protestant dialogue and engagement.

Dr. Armstrong will be teaching the course on Introduction to Protestant Social Thought at Acton University 2011, and he will also be speaking at another local event here in Grand Rapids later this week. On Wednesday evening, Dr. Armstrong will discuss “Ecumenism and the Threat of Ideology.” Join us if you are able for a night of fun, fellowship, and discussion.

Dr. Armstrong blogs here and you can follow him on Twitter here.