Many Christian churches teach that salvation is as easy as acknowledging to God that you are a sinner and then saying a beautiful prayer about your belief in Jesus Christ. They say at that moment you will receive the Holy Spirit, be born again, and become a new creation. After completing this, they also say you are now in the Christian family and will live with God, Jesus, and the Holy Spirit in heaven for all of eternity, regardless of how you live your life from that point on.

For author Marty Vanderzanden, this teaching never sat well in his heart. He has always wondered if there was...