About the Contributor(s): Michael Root is Professor of Systematic Theology at The Catholic University of America and Executive Director of the Center for Catholic and Evangelical Theology. He was formerly the Director of the Institute for Ecumenical Research, Strasbourg, France. James J. Buckley is Professor of Theology at Loyola University Maryland. He has recently contributed to and edited (with Frederick Bauerschmidt and Trent Pomplun) The Blackwell Companion to Catholicism (2007). He is associate director of the Center for Catholic and Evangelical Theology.