Robert Letham (Ph.D., University of Aberdeen), formerly senior minister of Emmanuel Presbyterian Church, Wilmington, Delaware, teaches at Wales Evangelical School of Theology and continues as visiting professor of theology at Reformed Theological Seminary, Washington, D.C., and adjunct professor of systematic theology at Westminster Theological Seminary, Philadelphia. He is the author of a number of books, including The Work of Christ (InterVarsity Press, 1993), The Lord's Supper (2001) and The Holy Trinity (2004) (both Presbyterian & Reformed), and Through Western Eyes (Mentor, 2007).