Great question! And yes, there are some questions about the appropriateness of this book for Catholics.

First, in case anyone has never heard of it, The Purpose Driven Life by Rick Warren, pastor of the Saddleback Church in southern California, has sold millions of copies and earned him the moniker of “America’s pastor.” His book proposes a forty-day journey that will help seekers find the purpose for their life by helping the reader to connect with God and discover His purpose for their life.

While the book is based on Scripture (the Protestant version), there are some dangers for Catholics.

In this article, published by Ronald J. Rychlak, Professor of Law and associate dean for academic affairs at the University of Mississippi in This Rock Magazine, we are warned that Warren’s book is based on the Protestant idea of sola scriptura – which means that the Bible is the only authority in all matters – and that we can reliably discern God’s purpose for our life from Scripture alone.

“But Scripture is not a catechism,” Rychlak writes. “Rather, it is the inspired written testimony to the faith that had already been given to a living community, the Church.”

Rychlak cites the writing of John Henry Newman who pointed out that “The sacred text was never intended to teach doctrine but only to prove it and that, if we would learn doctrine, we must have recourse to the formularies of the Church, for instance, to the Catechism and to the Creeds (Apologia Pro Vita Sua , 1).”

For this reason, Catholics cannot accept the “Purpose-Driven” approach to Scripture.

“With access to the inseparable triad of Sacred Scripture, Sacred Tradition, and the Church's magisterium, the faithful Catholic stands firmly on the full gospel — all that Christ wanted us to believe and do — and escapes being blown around by private interpretations of Scripture, politically correct doctrines, and theological fads,” Rychlak writes.

Warren also reassures readers that "God won't ask about your religious background or doctrinal views. The only thing that will matter is, did you accept what Jesus did for you and did you learn to love and trust him?" All we need to do is “receive and believe” he says and suggests bowing the head and telling Jesus, “I believe in you and I receive you.”

But this too is problematic. While it will certainly sound plausible to a Catholic who doesn't have a firm grasp of the faith, they may not notice that  "Warren's assertions are themselves ‘doctrinal views’.”

Rychlak also wonders if Warren’s idea of eternal life is the same as Jesus who said "Not every one who says to me 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of my Father who is in heaven" (Matt. 7:21).

There's more to it than just a simple profession of faith, which could explain why Warren’s book makes so little mention of sin, damnation, repentance or the cross.

Warren’s book also claims that baptism is just symbolic and doesn’t actually do anything. "Baptism doesn't make you a member of God's family; only faith in Christ does that. Baptism shows you are part of God's family."

Not so, says Rychlak and points out that this assertion is in direct contradiction to Church teaching which proclaims that “The sacraments of the New Covenant are necessary for salvation" (CCC 1129, emphasis in original) because they are instituted by Christ himself (CCC 1114).

It also contradicts what Christ Himself taught when he said, "Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God" (John 3:5).

Rychlak concludes: “Whatever helpful personal encouragement Warren's teaching might offer, the use of his books in any catechetical setting is a serious mistake. They are misleading and potentially profoundly confusing to poorly catechized Catholics. Moreover, while seeming to be ecumenical in approach, they actually undermine true ecumenism because they gloss over serious theological problems.”

While it’s a laudable goal to seek unity among Christians, this unity must be based on truth, Rychlak says.

"Rather than Catholic truth, Warren is purveying spiritualized pop-psychology. The ‘Purpose-Driven’ church looks less like the one mystical body of Christ than a loose conglomeration of inspirational social clubs. That is why Catholics who follow the Purpose-Driven template are driving blind, and the road they follow is more likely to lead away from the Church than to a deeper practice of their faith.”