The Lotus Sūtra, fascicle 2, the 3rd chapter on “A Parable” states:

He who does not put faith in this sūtra and slanders it, [will commit the sin of exterminating the seed of Buddhahood in all the people in the whole world. Or, suppose those who frown at and harbor doubt about the teaching of this sūtra . . . despise, hold in contempt, hate, envy, and bear a deep grudge against those who read, recite, copy, and uphold this sūtra. What would such people get in return? You should listen carefully.] Such people will fall into the Hell of Incessant Suffering upon death, [where their suffering will last endlessly, for a kalpa after another… , until they fall into the world of beasts becoming a huge serpent as long as 500 yojana in length.]

The same sūtra, fascicle 7, the 20th chapter on the “Never Despising Bodhisattva” also asserts: “[Some of the four categories of Buddhists (monks, nuns, laymen and laywomen) had impure minds. They got angry, spoke ill of him, saying, ‘Where did this ignorant monk come from?’ They struck him with a stick, a piece of wood, a piece of tile or a stone.] They were tormented in the Hell of Incessant Suffering for as long as 1,000 kalpa for the sin of persecuting a practicer of the Lotus Sūtra.”

The Nirvana Sūtra, too, declares: “If one avoids good teachers who preach the True Dharma and instead takes refuge in false dharmas, one will sink into the Hell of Incessant Sufferings, undergoing all the sufferings with his huge body of 84,000 square yojana.”

Examining many sūtras, we thus see they all regard slandering the True Dharma the most serious crime. How sad it is that people [in Japan] all should wander out of the gate of the True Dharma into the prison of evil dharma! Such ignorance is causing everyone [in Japan, high and low,] to be pulled by the rope of evil teachings and caught forever by the net of slandering the True Dharma! In this life such wanderers are lost in the mist of delusions; in the next life they will sink to the bottom of flaming hell. How sad it is! How terrible it is!

You should promptly discard your false faith and take up the true and sole teaching of the Lotus Sūtra at once. Then this triple world of the unenlightened will all become Buddha lands. Will Buddha lands ever decay? All the worlds in the universe will become Pure Lands. Will Pure Lands ever be destroyed? When our country does not decay and the world is not destroyed, our bodies will be safe and our hearts tranquil. Believe these words and revere them!

Risshō Ankoku-ron, Treatise on Spreading Peace Throughout the Country by Establishing the True Dharma, Writings of Nichiren Shōnin, Doctrine 1, Pages 141-142

I have added an extensive quote from Risshō Ankoku-ron and another from Senji-shō, Selecting the Right time, to the postscript in Day 43 of 100 illustrating Nichiren’s doctrinal rationale for his belief that slanderers of the Lotus Sūtra should be put to death.

Below are some notes I want to include for future reference:

Three Ages after the death of the Buddha

In the Age of the True Dharma (the first ten-century period), the Buddha’s teaching is practiced and enlightenment can be attained; in the Age of the Semblance Dharma (the second ten-century period), the teaching is practiced but enlightenment is not possible; in the last period of 10,000 years (the Latter Age of Degeneration), the teaching exists but it is no longer practiced.

Six transcendental faculties of a Buddha, bodhisattva, or arhat

1. ability to go anywhere
2. heavenly eye
3. heavenly ear
4. ability to read other people’s mind
5. ability to know former lives
6. ability to destroy all evil passions.

Four stages of sainthood in Theravada Buddhism

1. sudaon, one entering the stream of enlightenment
2. shidagon, one who has destroyed gross evil passions and will be reborn in the human and heavenly realms once more before entering Nirvana
3. anagon, one who has destroyed more of his evil passions, and will not be reborn in the realm of desire (world of transmigration)
4. arakan (arhat), who has destroyed all his evil passions.