My prayer for rain challenge has been criticized on the basis of the following passages from Nichiren Daishonin's seminal writing, Repaying Debts of Gratitude:
"Answer: I, too, admire and believe in these various accomplishments of his. There are other men of old who possessed such uncanny powers. But the possession of such power does not indicate whether that person’s understanding of the Buddhist teaching is correct or not. Among the nonBuddhist believers of India there have been men who could pour all the waters of the Ganges River into their ear and keep it there for twelve years, or those who could drink the ocean dry, grasp the sun and moon in their hands, or change the disciples of Shakyamuni Buddha into oxen or sheep. But such powers only made them more arrogant than ever and caused them to create further karma to confine themselves in the sufferings of birth and death. It is men like these whomT’ien-t’ai is referring to when he says, “They seek after fame and profit and increase their illusions of thought and desire.”
The Chinese priest Fa-yün of Kuang- che-ssu temple could make it rain suddenly or cause flowers to bloom immediately, but Miao-lo writes of him, 'Though he could bring about a response in this way, his understanding still did not accord with the truth [of the Lotus Sutra]. 'When the Great Teacher T’ien-t’ai read the Lotus Sutra, soft rain began to fall in an instant, and the Great Teacher Dengyo caused sweet rain to fall within the space of three days. However, they did not say that because of such powers their understanding of the truth coincided with that of the Buddha.
Regardless of what unusual powers the Great Teacher Kobo may have had, he described the Lotus Sutra as a doctrine of childish theory and wrote that Shakyamuni Buddha was still in the region of darkness. Persons of wisdom and understanding should have nothing to do with such writings." (Repaying Debts of Gratitude)
Since I too, along with T'ien-t'ai and Dengyo, do not say that possessing such powers prove that my understanding of the truth coincides with that of the Buddha and, unlike Kobo, I have never described the Lotus Sutra as a doctrine of childish theory, this passage neither refers to me nor any votary of the Lotus Sutra. In addition, in The Three Tripitaka Masters Pray For Rain, Nichiren Daishonin praises Dengyo for defeating Gomyo in their prayer for rain challenge in which Dengyo succeeded in proving the power of the Lotus Sutra.