Even up to today, renowned Buddhist scholars like Ven Shengyan from Taiwan also share this kind of thinking. The ironic thing is that he himself is a Chan Master who professes lineage from the Caodong (Soto) branch of Chan Buddhism. He once wrote in his book "The Orthodox Beliefs of Buddhism" that "The enlightenment of Chan is not equal to attaining Buddhahood. At most it is only equal to attaining the pure Dharma eye; which is the Sotapanna (stream-entry) stage of sainthood in Theravada or the first Bhumi (plane) of enlightenment in Mahayana."
He goes on to say that "If we consider this from the Tiantai school viewpoint, then a Chan practitioner who has passed through the 3 stages of practice is only at the Resemblance State of enlightenment (4th of the 6 states of enlightenment in Tiantai theory). Even after they have broken through the black pit of Avijja (fundamental ignorance), they still need to become hermits to continue cultivating their sainthood. At this point they would have only completed one of the 3 Asankhya Kalpas (immeasurable eons) required to reach Buddhahood."
Sorry to say, I totally cannot accept such statements from a famous teacher like him. Ven Shengyan's misguided views on enlightenment reminds me of a certain Vinaya master named Yuan who challenged Ven Huihai on the same subject. This was how it went:
Yuan: Chan masters keep saying that "this very body is the Buddha", I think this is unacceptable. Because the scriptures say that Bodhisattas who have reached the 1st Bhumi are able to manifest themselves in a hundred Buddha worlds. Those who reach the 2nd Bhumi have this power increased ten-fold. Why don't the master (refering to Hui Hai) try showing me some of this supernormal power?
Huihai: Acariya (teacher), are you yourself an ordinary person or a saint?
Yuan: I'm still an ordinary person.
Huihai: If you are an ordinary monk, how can you understand such states? The scriptures say, "Virtuous one, concepts of superiority & inferiority exists within your mind, and they are not in line with the Buddha's wisdom." This exactly describes you!
Yuan: Chan masters say that "If you realize the Dharma, with this very body you are liberated". I think this is unacceptable too.
Huihai: If a person does good throughout his life, but suddenly steals something into his hand; is he a thief in this very body?
Yuan: Of course.
Huihai: So if I clearly see my own Buddha-nature now, why can't I be liberated?
Yuan: Not right now, you still need to pass through the 3 Asankhya Kalpas before you can attain complete liberation.
Huihai: Can you count Asankhya (something immeasurable)?
Yuan: Then when you compared theft to liberation, is that comparison rational?
Huihai: Acariya, if you cannot see the Dharma, do not obstuct everyone from understanding it. If your eyes are closed, do not hate everybody who is able to see things.
At this, Yuan left in anger, saying that Huihai was an old fool without any Dharma. Huihai remarked "that" which had left is Yuan's Dharma. (end)
I feel sad for Ven Shengyan for he clings to doctrinal concepts which are only words, and presumptiously judges the wisdom of the past Buddhas & Patriarches with them. The scriptures say: "Do not slander Panna, for such a sin is limitless." It is indeed dangerous to try defining the Buddha-nature by mere scriptural knowledge instead of directly seeing it in your own heart through meditation. The Sutra of Complete Enlightenment says:
"Good man, the heart of complete enlightenment of all Buddhas is devoid of Bodhi & Nibbana; neither is there a concept of attaining or not attaining Buddhahood, not even a concept of false Samsara or not Samsara exists. Good man, even all the enlightened Savaka Arahants, with their mind, body & speech gone into extinction, cannot fathom the Nibbana that I have attained on my own. What more for ordinary people, with their conventional thinking, trying to define the completely enlightened state of the Tathagata? This is like trying to use a firefly's flame to burn Mount Sumeru - totally impossible to set alight. Or with the Samsaric mind producing Samsaric views, trying to enter the Tathagata's ocean of Nibbana - also completely impossible to reach. That is why I preach to all Bodhisattas & future sentient beings: destroy the root of Samsara (Avijja) that is without beginning first."
Thus, one must believe that Enlightenment is possible in 1 lifetime. The Supreme Dhamma is in each and everyone of us, and if you are determined enough to see it, it will reveal itself to you when the time is ripe. The transmission of Chan is beyond words & concepts. If Ven Shengyan forsake his book knowledge and look hard within his mind, he too will see the Buddha-nature one day, sadhu.