The Dalai Lama states in his The Opening of the Wisdom-Eye that Tibetan Buddhist teachings and rituals "were taught by Lord Buddha in person." This claim has two serious weaknesses. First, there are the crucial differences in belief and ritual between the late Buddhism of Tibet and the earlier Buddhisms of India and Sri Lanka, in addition to variants in China and Japan. For example, Tibetan Buddhist tantric ritual, including visualization of wrathful deities, lacks harmony with earlier forms of Buddhist meditation.

There is the deeper question of the historical integrity of the earliest documents about Buddha. These texts, in Pali and Sanskrit, were written between four and five centuries after the death of Gautama. In A Short History of Buddhism, the devout Buddhist scholar Edward Conze dismisses any "confident assertions" about what the Buddha really said as "mere guesswork." Conze wrote in his introduction to the Buddhist Scriptures: "Buddhists possess nothing that corresponds to the New Testament."

Aspects of Tibetan spirituality also give a Christian pause. The Tibetan emphasis on contact with spirit mediums is a case in point. The Dalai Lama himself regularly consults with the Nechung Oracle, said to be a spirit deity who takes over the body of a chosen Tibetan Buddhist. Furthermore, as missionary Mark Tsering documents, many Tibetan Buddhists have a superstitious fear about the spirit world (a result of the animist influence of Tibet's Bon religion) and a magical view of reality—as if the number of prostrations and countless turns of a prayer wheel is all it takes to affect the ever-pervasive ...