Let’s just think this out…
Zen is the accessing of intuitive Wisdom or that flowing into Intuitive ‘Buddha-Nature’ as Zen students like to call it. Zen is not a conceptual thing, you cannot say it’s a ‘thing’ or a thought, or even a philosophy.
This ‘Buddha-nature’ that Zen students like to talk about…what is that? Honestly, it is nothing more than Enlightenment (Awakened) itself, that of direct spirit that is not of this phenomenal caporal existence, is transcendent and eternal.
This phenomenal existence is what? Nothing more than enlightenment that forgot what it is, that congeals to become this crude matter that this body is built upon. The animus that moves this body is what? It is buddha-nature, a wind of enlightenment that touches and ever so slightly connects – thus the animation of this body Skandhas and we have a dream-like remembrance of enlightenment and a drive to reconnect.
Buddhism is a lot of things: Morality, virtues, social and civic instructions, as well as a spiritual path that is interpreted in many different ways and through the lens of different cultures.
One can say ‘Zen is Buddhism’ if one chooses to interpret Buddhism through the lens of Zen, as one can say that Buddhism is NOT-Zen through a different lens of interpretation. Yet, Zen in any view through any lens of interpretation still sees this ‘vital energy’ that is mystical in nature and connected to all things.
True, some interpret Zen to be nothing more than knowledge, reading the sayings of old zen masters (who decides who is a Zen master?), and knowing the history of Zen (who says what the history is?). Others say that Zen is just ‘No-mind’, just the unconceived aspect of mind, a philosophy at best. Yet, this is not Zen, rather just the Philosophy of Zen as I can speak to the philosophy of Anything without actually having to master anything at all. (sophism)
Yes, The Buddha (spiritually wakened one) Sidhartha Gautama was a Zen master, though, became the Vairocana when what was Sidhartha disappeared and all that was left was ‘Buddha-nature’ that flowed through his skandhas and where he preached the dharma.
So, Zen can be a religion, wrapped in mystique and mystery, shrouded by secret societies and occultic teachings. But it does not have to be this way at all, and some find Zen completely outside of religion too.
It is easy to become a zealot, to abide in the extremes when it comes to the views of Zen. This is where I would say to take the Middle Path, to not abide in the extremes, and to find a balance between the views. For in that middle way great wisdom is revealed as is knowledge gained.
Finally, Zen is not the domain of Japanese Religion or Chinese mysticism. Those who insist that Zen is that of the Far-east or Asian simply are clueless and blithering idiots! Ignore them, for they will just lead those who are foolish enough to listen to them down a path of folly and disaster!
Zen is for you to own! It is yours to develop and to master, and only you can do this. No master can do it for you, and no teacher can give you zen.