"Many Christians think that this world is not their home, this life is not what really matters, and only spiritual things last forever," Michael Wittmer says. And those Christians are what believers in past generations would call heretics.

Wittmer, associate professor of systematic theology at Grand Rapids Theological Seminary in Grand Rapids, Michigan, has just published his first book, Heaven Is a Place on Earth (Zondervan, $16.99). In it, he's challenging many evangelicals' attitudes toward life on earth, future in heaven, and how to live each day as a child of God.

"Many Christians have unwittingly adopted a dualistic, Gnostic view of the world," Wittmer says,. "Consequently, Christians think they only please God when they are witnessing, reading the Bible, praying, or attending church."

According to Wittmer, this dualism between spirit and body, heaven and earth, has thoroughly permeated evangelicalism, as evidenced by statements in Rick Warren's wildly popular book, The Purpose Driven Life.

While appreciative of much of what he writes, Wittmer takes issue with Warren's view that: "Your earthly body is just a temporary residence for your spirit" (p. 37), "Life on earth is a temporary assignment" (p. 47), and those Christians who think earth is their home "have betrayed their King" (p. 49).

"Warren commits a common evangelical mistake when he interprets the term 'world' (1 John 2:15), 'aliens and strangers' (1 Pet. 2:11), and 'earthly things' (Col. 3:2) in an ontological (literal) rather than moral sense," Wittmer says. "So whereas Scripture warns us to flee from sin in the world, Warren concludes that we must also avoid feeling at home in the physical world. Such thinking does not arise from the Christian gospel, but from ...