As all Mahāyāna sūtras except one do not preach on the basis of the “revealing the truth and merging all the provisional” doctrine, neither the doctrine of obtaining Buddhahood for the Two Vehicles nor that of attainment of Buddhahood by Śākyamuni Buddha in the eternal past is preached in them. The Lotus Sūtra on the other hand, is expounded on the basis of the “revealing the truth and merging all the provisional” doctrine, thus both doctrines of attaining Buddhahood by the Two Vehicles and the attainment of Buddhahood by Śākyamuni Buddha in the eternal past are revealed in it. Accordingly, it would be the sin of slandering the dharma for followers of those Mahāyāna sūtras to criticize the Lotus Sūtra, but criticism of those Mahāyāna sūtras by believers of the Lotus Sūtra does not constitute slander of the dharma.

Ken Hōbō-shō, A Clarificaton of Slandering the True Dharma, Writings of Nichiren Shōnin, Doctrine 3, Pages 133.

[T]he most important thing for non-Buddhist teachings is, like Confucianism, to prepare the way to Buddhism. This is why some non-Buddhists maintain that the Buddha will be born 1,000 years later, while others insist on 100 years later. It is said, therefore, in the Nirvana Sūtra that what is written in all the non-Buddhist scriptures is nothing but the teaching of the Buddha. Again, it is said in the Lotus Sūtra, chapter eight, “Assurance of Future Buddhahood,” that disciples of the Buddha sometimes pretend to be contaminated with the Three Poisons of greed, anger, and ignorance or show the heretic view denying the law of cause and effect as an expedient means to save the people.

Kaimoku-shō, Open Your Eyes to the Lotus Teaching, Writings of Nichiren Shōnin, Doctrine 2, Page 33

[W]e know that being aware of the past and future precisely is the qualification to be a sage. Without doubt, Śākyamuni Buddha knew that he would pass away in three months in the near future, and he also foretold that the Lotus Sūtra would spread widely in the Latter Age of Degeneration in the far future. Therefore, He could predict things in the far future with His ability of predicting things in the near future or foretell the future state with the knowledge of the present state. This is what the “Expedients” chapter of the Lotus Sūtra expounds, “The truth of all things consists of their appearances, natures … and their consistency from beginning to end.” Who then should be considered as a practicer of the Lotus Sūtra in the last 500-year period? I do not consider myself to be a man of wisdom. However, I can trust my wisdom concerning my predictions of domestic disturbance and foreign invasion. This is not to be bragged about to others. I hope that my disciples understand this. I, Nichiren, am the practicer of the Lotus Sūtra in the Latter Age of Degeneration. Since I follow the footsteps of Bodhisattva Never-Despising, anyone who despises or slanders me, will have his head broken into seven pieces. Whoever believes me, however, will accumulate merit as high as Mount Sumeru.

Shōnin Chi-sanze-ji, The Sage Knows the Three Periods, Writings of Nichiren Shōnin, Biography and Disciples, Volume 5, Pages 20

Just as drops of water fall to become rivers flowing into an ocean and dust particles accumulating to form Mt. Sumeru, the contention of the one person attached to a provisional sūtra will gradually increase, the number of people who do not believe in the true teaching will increase, and even the believers of the true teaching will fall back to believing in the provisional teaching. When believers of the provisional sūtras thus fill the country, the heart of rejoicing at hearing the Lotus Sūtra will be lost and it will be like a country without a king or a human being without spirit. The Lotus-Shingon temples will all fall into disrepair, divine protection by heavenly kings, virtuous gods, dragon god and others will disappear, and sages will all abandon the country. Taking advantage of the situation, devils and demons will take hold of the country, where evil winds will stop staple grains from ripening, and epidemics will spread to lead the people to ruin.

Shō Hokke Daimoku-shō, Treastise on Chanting the Daimoku of the Lotus Sūtra, Writings of Nichiren Shōnin, Faith and Practice, Volume 4, Page 16-17

The Lotus Sūtra of the fifth period consists of one fascicle of the Sūtra of Infinite Meaning as an introduction, eight fascicles of the Lotus Sūtra, and one fascicle of the Sūtra of Meditation on the Universal Sage Bodhisattva as the conclusion, bringing the total number of fascicles to ten.

The reason for my commentaries on the Four Teachings (Tripiṭaka, Common, Distinct, and Perfect) and the Four Periods (Flower Garland, Agama, Expanded, and Wisdom) is to help others learn what the Lotus Sūtra is. For one cannot correctly understand the teaching of the Lotus Sūtra without learning the pre-Lotus Sūtras, although one may study the pre-Lotus Sūtras without learning about other Sūtras.

In support of this, Grand Master T’ien-t’ai stated in his Profound Meaning of the Lotus Sūtra, “When attempting to spread various sūtras other than the Lotus Sūtra, the essential part of the teaching will not be lost even if a doctrinal analysis of all the teachings of the Buddha is not rendered. When attempting to spread the Lotus Sūtra, however, the essence of the teaching may be lost if a doctrinal analysis is not made.” It is preached in the Lotus Sūtra (chapter 2, “Expedients”), “Although the Buddhas expound various teachings, it is for the purpose of leading the people into the world of the One Buddha Vehicle.” “Various teachings” here refer to all the pre-Lotus Sūtras. “For the purpose of leading the people into the world of the One Buddha Vehicle” means to expound all the scriptures of Buddhism to reveal the Lotus Sūtra.

Ichidai Shōgyō Tai-I, Outline of All the Holy Teachings of the Buddha, Writings of Nichiren Shōnin, Doctrine 3, Page 81

A man should respect these three: his ruler, his teacher, and his parents. Everyone should study these three disciplines: Confucianism, non-Buddhist teachings and Buddhism. …

I-shou was the teacher of Yao, Wu-shih was that of Shun, T’ai-kungwang was of King Wen of Chou, and Lao-tzu was of Confucius. They were called the Four Sages. Even the kings and rulers, who were most respected under heaven, bowed low and all the people respectfully held their hands together in front of them. …

These wise and holy men are sages, but they are as ignorant of the past just as ordinary men cannot see their backs, and they cannot see into the future just as blind men cannot see in front. They merely maintain that if one manages his house well, performs filial devotions, and practices the Five Virtues (benevolence, righteousness, politeness, wisdom and fidelity) in this world, people will revere him, and his fame will spread so widely in the land that a wise king will invite him to be his minister or teacher, or even put him on the throne. Even heaven will come to defend and serve him! …

Ignorant of the past and future, however, these sages cannot help in the future lives of their parents, rulers and teachers. Not knowing what they owe to them in the past, they cannot be considered truly holy and wise. This is why Confucius said, “Truly wise and holy men do not exist in China, but in the land to the west, there is a man called Buddha. He is a true sage.”

Confucius thus indicated Confucianism, which is non-Buddhist (geten), to be the first step toward Buddhism. It would be easier, Confucius knew, for the people to understand the fundamental Buddhist teachings of commandments, meditation, and wisdom if they first learned the fundamental Confucian concepts of rituals and music. He therefore taught the kings’ subjects to be loyal to their rulers, children to be devoted to their parents, and students to respect their teachers. Grand Master Miao-lê therefore declared in his Annotations on the Great Concentration and Insight: “The dissemination of Buddhism in China indeed depended on Confucianism. Buddhism found its way by following on the heels of the rituals and music of Confucianism.”

Kaimoku-shō, Open Your Eyes to the Lotus Teaching, Writings of Nichiren Shōnin, Doctrine 2, Page 30-32

According to Buddhist sūtras, the Buddha’s tongue is as grand as to cover His whole face, as expansive as to cover the triple thousand worlds, and as lengthy as to reach the Summit Heaven in the Region of Form. It is a mark of physical excellence showing that the Buddha has never uttered a false word ever since the eternal past. Therefore, it is preached in a certain sūtra, “There exists no falsehood in the words of the Buddha even if Mt. Sumeru crumbles or if the earth is overturned.” This means that there is never a mistake in the words of the Buddha even if the sun rises in the west or the ebb and flow of the tide in an ocean stop, does it not? Moreover, the superiority of the Lotus Sūtra over various other sūtras has been confirmed by the words of the Buddha of Many Treasures, and the long tongues of other Buddhas touching the Brahma Heaven. There must not be any mistake in the sūtra, not even one written character or one stroke of a character.

Ueno-dono Gohenji, Reply to Lord Ueno, Writings of Nichiren Shōnin, Volume 7, Followers II, Page 4

To begin with, the strange phenomena in the sky and the natural calamities on the earth startle the eyes and ears of the people and rattle their minds. Śākyamuni Buddha has caused the five or six kinds of omens to occur. Among the six omens, the trembling of the earth indicates that the earth trembled in six different ways. Interpreting the earth trembling in six ways, Grand Master T’ien-t’ai states in his Words and Phrases of the Lotus Sūtra, fascicle 3:

“The east is blue in color, and it controls the liver, which in turn controls the eyes. The west is white in color, and it controls the lungs, which in turn control the nose. Therefore, saying that the east was raised and the west was lowered means the rise of the merit of the eyes and the decrease in the worldly passions of the nose. In contrast, saying that the west was raised and the east was lowered means that the merit of the nose appears while the evil passions of the eyes decrease. Likewise, the rise and fall of the south and north and those of the center and the four directions mean either the appearance of merit or the decrease of evil passions in the ears and the tongue and in the mind and body respectively.”

Grand Master Miao-lê explains the above in his Annotations on the Words and Phrases of the Lotus Sūtra, “As the eyes and nose represent the east and west, the ears and tongue logically represent the south and north. The center is the mind and the four directions represent the body. The body is equipped with the four sense organs (eyes, ears, nose, and tongue) and the mind reacts to them all. Therefore, it is said that the body and mind rise and fall alternately.”

Zuisō Gosho, Writing on Omens, Writings of Nichiren Shōnin, Followers I, Volume 6, Page 121