Warning: Beware the used or library textbook with highlighting. Do the human race a favor and don't highlight your books. As for selling back your textbooks: "Buy truth, and do not sell it" (Proverbs 23:23).
Required Reading for All Students:
William H. Willimon et al., Lord Teach Us, Abingdon, 1996.
Lesslie Newbigin, The Light Has Come, Eerdmans, 1982. "Our Father."
Benedict XVI, God Is Love, USCCB, 2006. "Hallowed be your name."
Stanley Hauerwas, Peaceable Kingdom, Notre Dame, 1984 or 2d ed., SCM, 2003. "Your Kingdom come."
Gerhard O. Forde, On Being a Theologian of the Cross, Eerdmans, 1997. "Your will be done on earth."
Volker Kuster, The Many Faces of Jesus Christ: An Intercultural Christology, Orbis, 2001. "Give us today our daily bread."
Miroslav Volf, Free of Charge, Zondervan, 2006. "Forgive us our sins."
David Kelsey, Imagining Redemption, WJK, 2005. "Deliver us from evil."
Paul Blowers, ed., On the Cosmic Mystery of Christ: Selected Writings from St. Maximus the Confessor, SVS, 2004. "For yours is the kingdom, the power, and the glory."
For students improving their writing skills, my upper-division classes feature conditionally required reading.