Nichiren is known primarily for his advocacy of the Lotus Sūtra as the Buddha’s highest teaching and for the practice of chanting its Odaimoku (lit. sacred title) in the form of Namu Myōhō Renge Kyō (lit. Devotion to the Sūtra of the Lotus Flower of the Wonderful Dharma). He is also known for his denunciation of other schools of Buddhism. This denunciation is often summarized in the form of the “four admonitions” (J. shika no kakugen):

Pure Land Buddhism is a way leading to the Hell of Incessant Suffering; Zen Buddhism is the act of heavenly devils, who hinder the Buddhist way; Mantra (Shingon) Buddhism is an evil teaching leading to the destruction of our nation; and Discipline (Ritsu) Buddhism is a false teaching by traitors. (Hori 1992, p. 178 adapted)