How does chanting work in Nichiren Buddhism? This question came up in my book club.

Chanting is a central practice in Nichiren Buddhism. How does it work, what effects or benefits come from it?  Has this changed much between from historical and modern times?
Incidentally, Nipponzan-Myōhōji, a modern religious movement that emerged from Nichiren sect, was my first contact with real-life Buddhist practice. In Nichiren, chanting NA-MU-MYO! HO! REN! GE! KYO! is revered as a symbol of what they call "the true cause of Buddhahood". The idea being, if one never hears about Enlightenment one cannot get onto the path, so in each individual case of Enlightenment, the process must have started with someone dropping the word which planted the seed in the student's mind.

Nichiren (the founder) must have thought very low of his times -- chanting a title of a sutra(!) sounds like a suitable teaching for hell, the inhabitants of which would otherwise have no chance of asking "What does this mean, NA-MU-MYO-HO-REN-GE-KYO? Hm... glory to the Sutra of the Lotus of the True Dharma... So what is this True Dharma thing?" question.

A contemporary Buddhist teacher my friend Dennis Wallez explains:


  Indeed Japan was quite in disarray at the time, torn by wars and famine and persecutions... Nichiren thought this partly was the karmic consequences of the perversion of Buddhism by previous schools. The notion of "Latter days of the dharma" was in full swing too and many teachers saw the local situation as a confirmation...


So to summarize, in Nichiren chanting is both a symbol and practice of seeding the basic seeds, a seemingly primitive work that is never beneath a compassionate Bodhisattva.

This is why Terasawa Junsei, a prominent teacher of Nipponzan-Myōhōji, was (and still is) such a big advocate of chanting NA-MU-MYO-HO-REN-GE-KYO in public, especially in troubled areas such as zones of armed conflicts.