Three Christian thinkers discuss some of the fundamental issues of prayer, including why we should pray, to whom and how. In one illuminating exchange, the three focus on questions about unanswered prayer. Myra is editorial director of the Christianity Today publishing empire. Nystrom has written dozens of books, including “Praying: Finding Our Way Through Duty to Delight,” (InterVarsity Press, 2003) co-authored with J. I. Packer. Eble is the author of 11 books, most recently “Abundant Gifts,” published in 2004. Matera is a writer and author.