Beyond Belief / The Secret Gospel of Thomas, published in 2003 by Vintage Books, written by Elaine Pagels.  This book compares the Gospel of John and the Gospel of Thomas, one of the ancient texts found at Nag Hammadi, Egypt, in 1945. 

The Gospel of Thomas has generated much interest because it is (arguably) a Gnostic Gospel that challenges the Gospel of John. The Gospel of John is important because it establishes the absolute divinity of Jesus. It is the Gospel that, as a result of the intense persuasion by Irenaeus of Lyons, the father of Christian Orthodoxy, has become the most important and most revered of the four Biblical Gospels. 

Thomas teaches that an ‘affinity’ for God, achieved through intuition or meditation, is the key to entering the Kingdom of God, rather than accepting Jesus as the only path to salvation. Thomas emphasizes that the Kingdom of God is not a future event but exists here and now. Everyone can participate in the glory of the Kingdom through self-discovery and exploring their soul for spiritual truth.

Thomas teaches that Jesus is revered as a messenger from God and a unique spiritual teacher, but is not viewed as the only path to knowing God. This idea sharply conflicts with the divinity doctrine emphasized by John and Paul of Tarsus. Since the Gospel of John and the synoptic Gospels form the foundation of Christian orthodoxy, the alternative perspective of the Gospel of Thomas introduces a disruptive and impactful wave in the sea of Christian teachings.

The Gospel of Thomas is believed to have been hidden by being buried underground during a period when views other than the accepted interpretations of early Christian teachings were considered heretical, a movement led by Athanasius, the loudest proponent of trinitarianism.

Elaine Pagels is a historian of religion who has conducted extensive research on early Christianity and Gnosticism. She was educated at Stanford and took her PhD from Harvard. She is recognized as an expert in her field of research. She also authored other books, including The Gnostic Gospels, published in 1979.