He has served in many churches in the Texas Conference and currently participates at Trinity United Methodist Church. He holds degrees from the University of Houston (B.S. History and Philosophy), and Perkins School of Theology at SMU (B.D., D.Min.). A past contributor to The Immediate Word, part of CSS Publishing's online pastor resource SermonSuite (sermonsuite.com), Killen's interests include writing, walking, and bird watching.