Her "New York Times" bestseller, "Beyond Belief: The Secret Gospel of Thomas" (2003), contrasts the Gospel of Thomas with the Gospel of John, and argues that a close reading of the works shows that while the Gospel of Thomas taught its adherents that "there is a light within each person, and it lights up the whole universe [-] If it does not shine, there is darkness", the Gospel of John emphasizes the revelation that God as Jesus Christ is the "light of the world". On Pagels' interpretation, the Gospel of Thomas claims, along with other non-canonical teachings, that Jesus was not God, but rather, a human teacher who sought to uncover the divine light in all human beings. This non-canonical viewpoint is in contradiction with the four New Testament gospels. Pagels argues that the Gospel of John was written as a rebuttal to the viewpoints put forth in the non-canonical Gospel of Thomas. She bases her conclusion on the theory that, in the Gospel of John, the apostle Thomas is portrayed as a disciple of little faith who cannot believe without seeing and, that the Gospel of John places an emphasis on Divine Jesus Christ as the center of belief, which Pagels views as a hallmark of early orthodoxy. "Beyond Belief" also includes Pagels' personal exploration of meaning during a time of loss and tragedy.