[I]n the first fascicle of the Lotus Sūtra proper, it is preached: “The Buddha will expound the truth after preaching for a long time” and “He will solely expound the supreme way, honestly discarding the expedient teaching.” This means that it is only the Lotus Sūtra that is true. It is like a full moon appearing in the dark night, or the disassembling of a scaffold after the construction of a huge tower. Later, Śākyamuni Buddha expounded the truth saying:
“This Sahā World is My domain and the living beings in it are all My children. This world, however, is full of suffering and pain. It is only I, the Buddha, who can save all living beings suffering in this world. Having wandered out of the right way and losing rationality, they refuse to accept My guidance and persuasion. Instead, they slight, or show contempt for, hate, are envious of and bear grudges against those who recite and uphold the Lotus Sūtra. Such people will surely fall into the Avīci Hell.”
The way in which this sūtra is preached differs from the teachings in ordinary sūtras. Usually those who commit the five rebellious or seven rebellious sins are said to fall into the Hell of Incessant Suffering, but this sūtra does not say so. It preaches that of all the people in the Buddha’s lifetime and after His extinction, those who do not believe in the Lotus Sūtra and adhere to such provisional teachings as the Amitābha Sūtra preached during the forty years or so before the Lotus Sūtra was preached, or those who believe in the Lotus Sūtra but cannot relinquish faith in the provisional teachings, and practice the Lotus Sūtra and the provisional teachings at the same time, or those who claim that the provisional teachings they believe in are superior to the Lotus Sūtra, or those who despise and abuse the people who practice the Lotus Sūtra by saying they are not practicers of the Lotus Sūtra—all these people “will surely fall into the Hell of Incessant Suffering upon death.”
Shimoyama Goshōsoku, The Shimoyama Letter, Writings of Nichiren Shōnin, Volume 5, Page 88