Hi Rodrigo -
My first instinct here was to say that while it certainly is possible, I would also say it is not at all likely.
From what I can tell, none of Shakyamuni's disciples who were there at Vulture Peak that day left their self-power Buddhist lives behind, as Master Shinran did.
And most Pure Land Buddhists since then haven't understood the Larger Sutra properly either - even though the Larger Sutra is the core of all the Pure Land schools.
The problem is that when you read the Larger Sutra, without having some additional guidance, it is not at all obvious that the key to the whole thing - and to the work of Amida Himself - is the 18th or Primal Vow. And as you read the Sutra, Shakyamuni gives plenty of self-power oriented teachings - particularly in the second half of the Sutra - for those who will only be able to become people of the 19th and 20th Vow, but not the 18th...YET.
This is exactly what Master Rennyo was pointing at when he gave his five conditions for birth - aka receiving Shinjin in this life, and then becoming a Buddha in the life to come.
And as I just re-read this letter for the umpteenth time (see below), I changed my answer. Now, based on my reading of Master Rennyo's words, I would say it is NOT possible to become a person of Shinjin simply by reading the Larger Sutra. A person MUST encounter a good teacher.
Let's listen together:
Facsicle 2:11 - On the Fivefold Teaching
In recent years, the import of the teaching of our tradition’s Master Shinran has been presented in various ways in the provinces, with a lack of uniformity. This is a most deplorable situation.
For, to begin with, although the birth of ordinary beings [in the Pure Land] through other-power faith has been of primary importance in our tradition, [some] brush aside the matter of faith and do not consider it. They propose that “faith is not forgetting that Amida Tathagata settled our birth at the time of his perfect enlightenment ten kalpas ago.”
What is completely lacking in this is the element of taking refuge in Amida and realizing other-power faith. Therefore however well they may know that their birth has been settled since the time of [Amida’s] perfect enlightenment ten kalpas ago, unless they fully know the significance of other-power faith, through which we attain birth, they will not attain birth in the Land of Utmost Bliss.
There are also some people who say, “Even if we take refuge in Amida, this is to no avail without a good teacher. Therefore, there is nothing for us to do but rely on a good teacher.” These are their words. They, too, are people who have not properly attained our tradition’s faith.
The function of a good teacher is just to encourage people to take refuge in Amida singleheartedly and steadfastly.
Therefore a fivefold teaching has been established [giving the conditions necessary for birth]:
- first, [the unfolding of] good from the past;
- second, [meeting] a good teacher;
- third, [encountering Amida’s] light;
- fourth, [attaining] faith;
- and, fifth, [saying] the Name [of the Buddha].
Unless this fivefold teaching is realized, it is evident [in the received texts] that birth is impossible.
Thus the good teacher is the messenger who tells us to take refuge in Amida Buddha. Without meeting a good teacher through the unfolding of good from the past, birth is impossible.
Bear in mind, however, that to abandon Amida, in whom we take refuge, and to take only the good teacher as essential is a serious error.
Now, this doesn't imply we must meet a good teacher IN THE FLESH. The example that comes to mind is Master Honen, young Shinran's own Dharma mentor. When he became unsatisfied with his own progress on the self-power path - aka the Path of the Sages - there was not a single living person he could turn to who was a person of Shinjin. He had no LIVING teacher of the True Teaching of the Pure Land Way to guide him along.
But he did have access to the great Buddhist libraries of the day. And as he dug through the ancient texts, he DID find teachers - the earlier Pure Land Masters such as Nagarjuna, Vasubandu, Tan-Lu'an, Tao-Cho, Shan-Tao, and Genshin, who were able to provide him the guidance he needed (and we all need) to rightly understand the Larger Sutra.
And, as you can see, in Master Rennyo's eyes, the requirements for being a TRUE Dharma teacher in our school are ridiculously simple. As I've said many many times (quoting Rennyo himself), we just need to be people of Shinjin, committing to sharing the pristine Dharma without making any divergences from it.
And what we need to be able to share, as teachers, is also ridiculously simple - literally ANYONE can do it, once they have received Amida's gift for themselves.
Of course, those of us who are people of Shinjin don't need to understand everything, and shouldn't feel compelled to teach out of our own intellectual depth. There are a lot of passages that I read that I will not understand fully or properly until I too become a Buddha in Amida's Pure Land.
But we don't have to understand everything. All we need to understand are the BASICS. Amida designed this new paradigm Buddhism in just that way, so as to level the playing field and make Buddhahood easily accessible to ALL.
So...if you are a person of Shinjin, you are truly "licensed to teach" by Amida Buddha Himself. You don't HAVE to teach, if you never feel so led. TRUE Shin Buddhism is certainly not a path of religious obligations.
But as Amida leads, and a door is opened, you are as competent as anybody else to share the BASICS of our faith...and if the one you are sharing with is responding to Amida's call, that will be ENOUGH.