Passage: Craig joined the faculty of Trinity Evangelical Divinity School in 1980, where he taught philosophy of religion for the next seven years. In 1982 Craig received an invitation to debate Kai Nielsen at the University of Calgary, Canada, on the question of God's existence, and has since then debated many philosophers, scientists, and biblical scholars After a one-year stint at Westmont College on the outskirts of Santa Barbara, Craig moved in 1987 with his wife and two young children back to Europe, where he pursued research for the next seven years as a visiting scholar at the Katholieke Universiteit Leuven (Louvain) in Belgium. Out of that period of research issued seven books, among them God, Time, and Eternity (2001). In 1994, Craig joined the Department of Philosophy and Ethics at Talbot School of Theology in suburban Los Angeles as a Research Professor of Philosophy, a position he currently holds, and he went on to become a Professor of Philosophy at Houston Baptist University in 2014. In 2016, Craig was named Alumnus of the Year by Trinity Evangelical Divinity School. In 2017, Biola created a permanent faculty position and endowed chair, the William Lane Craig Endowed Chair in Philosophy, in honor of Craig's academic contributions.Craig served as president of the Philosophy of Time Society from 1999 to 2006. He helped found the Evangelical Philosophical Society and served as its president from 1996 to 2005.

Question: How many written works did Craig produce during his time in Belgium?
seven