When you kill the body (Lotus Sutra), the heart (Namu Myoho renge kyo) dies.

Likewise, when you kill the heart (Namu Myoho renge kyo) the body dies,

"Question: Of the twenty-eight chapters of the Lotus Sutra, which is the heart, which is the most essential?

Answer: Some would say that each chapter is essential to the matter that it deals with. Some would contend that the “Expedient Means” and “Life Span” chapters are the heart, others that the “Expedient Means” alone is the heart, or that the “Life Span” alone is the heart. Some would say that the heart is the passage telling how the Buddhas open the door of Buddha wisdom to all living beings, show it, cause them to awaken to it, and induce them to enter its path, others that the passage on the “true aspect of all phenomena” is the heart.

Question: What is your opinion?

Answer: I believe that the words Namu-myoho-renge-kyo constitute the heart.

Question: What is your proof?

Answer: The fact that Ānanda, Manjushrī, and the others wrote, “This is what I heard.”

Question: What do you mean by that?

Answer: Over a period of eight years, Ānanda, Manjushrī and the others listened to the immeasurable meanings of the Lotus Sutra, never missing a single phrase, a single verse, a single word. Yet, after the Buddha had passed away, at the time of the compilation of his teachings, when the 999 arhats took up their writing brushes and dipped them in ink, they first of all wrote “Myoho-renge-kyo,” and after that they intoned the words, “This is what I heard.” Therefore, the five characters of Myoho-renge-kyo must be the heart of the eight volumes and twenty-eight chapters that compose the work, must they not?

Therefore, the Dharma Teacher Fa-yün of Kuang-che-ssu temple, who is said to have lectured on the Lotus Sutra ever since the distant age of Sun Moon Bright Buddha, states, “The words ‘This is what I heard’ indicate that one is going to transmit the doctrines one has heard preached. The title, which precedes these words, sums up the sutra as a whole.”

The Great Teacher T’ien-t’ai, who was present on Eagle Peak when the Lotus Sutra was preached and heard it in person, writes, “The word ‘this’ [of ‘This is what I heard’] indicates the essence of a doctrine heard from the Buddha.” And the Great Teacher Chang-an writes, “The transcriber [Chang-an] comments on T’ien-t’ai’s explanation of the title of the Lotus Sutra, saying, ‘Hence [his explanation of the title in] the preface conveys the profound meaning of the sutra. The profound meaning indicates the heart of the text.’” 

In this passage, “the heart of the text” signifies that the daimoku, or title, of the text is the heart of the Lotus Sutra. As the Great Teacher Miao-lo states, “It is the heart of the Lotus Sutra that encompasses all the doctrines preached by the Buddha in the course of his lifetime.”

India comprises seventy states, but they are known collectively by the name India. Japan comprises sixty provinces, but they are known collectively by the name Japan. Within the name India are contained all the seventy states, as well as all their people, animals, treasures, and so forth. Within the name Japan are contained all the sixty-six provinces. The feathers sent as tribute from Dewa, the gold of the province of Mutsu, and all the other treasures of the nation, as well as the people and animals, and temples and shrines, are contained within the two characters that form the name Japan.

One who possesses the heavenly eye can look at the two characters of the name Japan and see all the sixty-six provinces along with their people and animals. One who possesses the Dharma eye can see all the people and animals now dying in one place, now being born in another place.

It is like hearing someone’s voice and knowing what the person must look like, or seeing someone’s footprints and judging whether the person is large or small. Or it is like estimating the size of a pond by looking at the lotuses that grow in it, or imagining the size of the dragons by observing the rain that they cause to fall. Each of these examples illustrates the principle that all things are expressed in one."

Commentary...

Please remember, when you kill the body [Lotus Sutra] the heart [Namu Myoho renge kyo] dies. SGI's interfaith and Guru Yoga kills the heart, Namu Myoho renge kyo.