The phrase mon soku shin (hearing turns to faith) is often used in True Pure Land School sermons. What does it mean?
Mon soku shin is an extremely important word referring to the time when Amida Buddha saves us into absolute happiness. It is stated that in the instant of hearing that Name, one attains faith and joy; the Vow of Amida Buddha saves all those who hear and believe. Hearing, therefore, is most crucial to Amida’s salvation. This is why Rennyo taught, as recorded in The Words of Rennyo Heard and Recorded during His Lifetime, that Buddhism begins and ends with hearing. One is saved in the instant of hearing: this is Buddhism.
The word Rennyo used, rendered above as “hearing,” is chōmon. This is a compound made up of two Chinese characters referring to two kinds of listening that are strictly differentiated in Buddhism. This point needs to be well understood. The first type means simply to listen and comprehend. This is the type of listening we engage in when we hear someone say that two plus two equals four, and four plus four equals eight. In order to encounter Amida’s salvation, it is important that we first listen to and comprehend the origin, beginning to end, of Amida Buddha’s Vow. This means that we need to know for whom Amida made his Vow, how he made his Vow, and what the outcome was. If we cannot comprehend this, we must listen repeatedly until we do. Since Buddhism is grounded upon the law of cause and effect, anyone can surely comprehend it, if they only listen. To begin with, the most important thing is listening to the teachings over and over until we understand them correctly and are persuaded of their truth. This is chō, the first part of chōmon. However, no matter how thoroughly we may understand and accept the teachings, that alone is mere acquisition of knowledge, which is not the same as Amida’s salvation. Rennyo put it this way:
What do you suppose chōmon to be? Only listening with the ears is not chōmon. The reason is that even if you listen a thousand or ten thousand times, if you do not acquire faith, you have not heard. Unless you acquire faith, you will not be born in the Pure Land. ----Isshū kokoroe no koto What is your view of chōmon? Just listening, comprehending, and acquiescing is not the same as chōmon. You may bend your ear a thousand or ten thousand times, but if you do not acquire faith, you still have not heard. If you do not acquire faith, you cannot go to Amida’s Pure Land. Though we may listen to a thousand or ten thousand sermons, such listening brings merely intellectual comprehension and acquiescence. Then what is the other sort of listening, the second half of chōmon? “Hearing” means that anyone at all hears the origin, beginning to end, of Amida’s Vow without a trace of doubt in his mind. This is “hearing.” ----Teaching, Practice, Faith, Enlightenment, Chapter on Faith, Part 2 (Paraphrase)
Mon (hearing) means that not a particle of doubt remains concerning the origin, beginning to end, of Amida’s Primal Vow. This is mon (hearing).
We are utterly inert corpses guilty of grave offenses and slandering Buddhism. But we are being moved just as we are through the unnamable, inexplicable, inconceivable power of the Vow. In the split-second when our doubt concerning the origin, beginning to end, of Amida’s primal Vow is completely dispelled (shin), we enter into vast security and complete fulfillment. Also, it is revealed to us that Śākyamuni’s eight thousand appearances in this world and all the many skillful ways and means were “for me alone.” This is what is called mon soku shin, hearing that means the acquisition of faith. Let us listen persistently until we acquire faith.
(Petals of Shinran, Wisteria Volume chapter 44)