Zhiyi had taught that the Lotus Sūtra has the function of “opening and integrating” (J. kaie) the three vehicles within the one vehicle. … Nichiren understood this as opening the nine realms to reveal the buddha realm. But what did it mean in terms of practice? Nichiren’s contemporaries often freely combined copying and reciting the Lotus Sūtra with nenbutsu chanting, esoteric rituals, and other modes of Buddhist devotion. For many Tendai scholars of the day, the distinction between true and provisional teachings did not mean renouncing practices other than the Lotus Sūtra. It would indeed be a mistake, they said, to recite other sūtras or chant the names of the various buddhas and bodhisattvas thinking that these represented separate truths. But the one vehicle of the Lotus Sūtra integrates all other teachings within itself, just as the great ocean gathers all rivers. Therefore, they claimed, any practice — whether esoteric ritual performance, sūtra copying, or nenbutsu recitation — in effect becomes the practice of the Lotus Sūtra when carried out with this understanding. Others, however, disagreed, and none more vocally than Nichiren. To argue his point, he inverted the “rivers and ocean” metaphor. Once integrated into the Lotus Sūtra, he said, the nenbutsu, esoteric rites, and other practices lose their identity as independent practices, just as the many rivers emptying into the ocean assume the same salty flavor and lose their original names. Precisely because provisional teachings are integrated into the all encompassing principle of the one vehicle, they are no longer to be practiced as independent forms. At the same time, however, Nichiren insisted that the daimoku contains all truth and blessings within itself. Because the daimoku is all-encompassing, chanting it would confer all the benefits that the religious practices of his day were thought to produce: this-worldly benefits such as protection and healing, assurance for the afterlife, and buddhahood itself. His aim was not to eradicate the spectrum of religious interpretations, but to undercut their basis in other traditions and assimilate them to the Lotus Sūtra alone.

Buddhist sūtras specify two approaches to teaching the dharma: shōju, or leading others gradually without criticizing their present stance, and shakubuku, or actively rebuking attachment to false views. The choice between them, Nichiren said, should depend on the time and place. In his view, in Japan at the beginning of the Final Dharma age — a time and place where the Lotus Sūtra was being rejected in favor of provisional teachings — the confrontational shakubuku method should take precedence over the more accommodating shōju approach.