Welcome,

With reference to the above quote and to explain, Advaita is not a religion (although Advaita-Vedanta is a teaching in Hindu scriptures). Advaita is a Sanskrit word which means 'not two', which describes, explains, and teaches that this existence is non-dual.

Advaita or nonduality is the knowledge of the realisation that the entirety of existence itself is a singularity (nothing other than one thing exists), meaning that in reality all ‘This’ (everything) is ‘One’ (there is not one thing or being that is truly seperate from any other).

Through these pages we hope to reveal the truth of nonduality for what we believe is good reason. We see nonduality as the fact. It is the truth. Truth is the basic requirement for lasting happiness.
All of the problems faced by humankind arise through forms of fear. Fear arises through the sensing of separation and division in society. The seeing of ‘another’ is at the root of all fear. Fear seeks control and gain over those ‘others’. Love becomes restricted to personal circles.

All of our senses report to our mind, therefore our understanding wants to deny that the world we experience could be nondual. our thinking alone cannot get to the fact we are all One. We engage with the world through our senses which are outward facing. We interact with ‘other’ things places and beings. In Sanskrit this seeing of ‘other’ and separation is described as being caused by Maya, which means a form of delusion or illusion in consciousness (sometimes compared to a dreaming).

We will endeavour to reveal the truth of nonduality through the use of logic, scriptures, science and philosophy. The ‘book’ the holy bible, the Hindu Upanishads, Buddhist scriptures, Muslim scripture (although more limited to groups such as The Sufis), quantum physics and other various sources, including Shakespeare will be referred to. The foundational scripture here will be the Upanishads because they were the main source of our learning and we believe they contain the most rational explanation and statements of nonduality. For this reason, we have included one of the greatest Upanishads, the Brihadaranyaka Upanishad (meaning the forest of wisdom) complete with the addition of our commentary to reveal its true purpose of teaching Advaita, nonduality. We will included other writings that also contain clear teachings of nonduality.

Caution

Discovering higher truths is every intelligent beings desire and part of our life journey. But, we also need to be aware and protective of our personal emotions. All of us, as we live, develop our own beliefs and understanding from what we have been taught. Even non-believers, atheists or agnostics become comfortable with their own notion of their reality. This is natural. Our acceptance of our existence or of our religion or our purpose enables us to live and face our day-to-day life. But, new insights to our long held comfortable beliefs can be profoundly disturbing. All such realisations could equate to losing one’s faith. Deep anxiety comes with challenges to our beliefs. We need to be prepared for this.
Non-duality doesn’t take away spiritual reality or God or the Absolute or afterlife etc. In fact, nonduality or Advaita, once realised gives a proof of divine existence that can be stronger than belief alone. This is what we have found and believe.

Why the fact of nonduality needs to be realised

Fear also arises through the perception of being alone, but in truth nonduality does not mean alone. Nonduality means all is one. Nondual means to be complete. Whereas duality, the seeing of ‘another’ can be to feel incomplete. The other could have some of your needs. Duality can lead to feelings of loneliness even in a crowd. In duality, with minds of separation religions become larger than the beings themselves. The dual mind allows ego to become self-serving. The seeing of name and form reinforces the perception of duality. There could be Trillions of life forms in the universe but there is only one Consciousness within which all life is 'experienced'.

There is no true birth and no death.

The process of the logic to the reality of nonduality starts from a state difficult to even imagine because it would be unreal. This is a state of non-existence, true nothingness anywhere. Such a state could never have been. But, the impossibility of there ever being such a state of non-existence is part of the very logic that supports non-duality. So, please contemplate as you read and enjoy.

This logic process is quite short, only a few sentences, but each word needs to be properly understood. Once the singularity of existence is realised many other truths become apparent.
First, we need to start by contemplating nothing in existence, not even existence itself. According to Wikipedia “Nothing, no-thing, or no thing, is the complete absence of anything; The opposite of everything, or its complement”. Now, there has never been such a state as we shall see, but we have to include it in our logic process. This state of absolute non-existence, nothing, does not mean emptiness or a vacuum all around. In non-existence there would be no empty, empty would not exist. All around would not exist. Vacuum would not exist. This fact of non-existence wouldn’t  have a future, because in non-existence, a future couldn’t exist. There would be no existence for a future to come from. Time would not exist. So, here we are properly understanding non-existence, this understanding is essential. We can now introduce the irrefutable statement that ‘nothing can come from nothing’. This must be perfectly reasonable. If there were ever to be nothing in the past, there must be nothing now. Where there is nothing existing, there is nothing to cause or allow ‘something’ to exist.

Now, today literally, we pick up a grain of sand, or a flower. Immediately, because of existence now we must accept that there never could have been a time or a state of nothing, of non-existence. Existence could not have come from no existence. This is of the greatest importance but hard for us to grasp and understand. This existence has always existed, it has always been. There never has been a beginning, therefore there can be no ending. This existence is timeless and eternal. It follows, as with the law of energy conservation, nothing new comes into existence and all that has existed, still exists now and can never go out of existence.
It follows, this eternal existence is just one, a unity without beginning, unborn and without cause. With this knowledge the absoluteness of existence comes into evidence. Being timeless and one only there can be no accident or coincidence. All that is can only be this way because it is supported by the knowledge as information that enables it. Being unchanging and timeless this knowledge must be absolute. Absolute knowledge as existence is absolute all-knowing consciousness.
Within this existence of Absolute Consciousness. One without a second. Unborn. Eternal. There could not be an atom or photon or a sparrow that is not eternally consciously known.

Further conclusions from the reality of nonduality.

Considering existence is a conscious experience, then there is only ever now. This may be hard to envisage but That that has no beginning cannot change. Therefore Absolute knowledge cannot change.
The totality of existence is now. What we regard as past present and future all exist now. Existence being without beginning. All possibilities regarding all events for all time have to have existed timelessly. Time does not exist in reality.
Although we experience a flow of events, cause and effect etc. All experience must occur in consciousness only. Dreams take place in consciousness. Sometimes one can experience a lifetime in a dream lasting seconds.

Due to the timelessness of existence there could be no process of learning, no increase or decrease in knowledge. Knowledge or information is an absolute of existence. Therefore knowing is absolute. Absolute knowing forms consciousness perfectly, absolutely. All of this is without movement without change this absolute is immutable therefore immortal. Nothing new, no change, can come into existence and nothing that exists, can go out of existence.

Nonduality in the scriptures.

The Upanishads in general are often referred to in our work. First of all, because the body of Advaita Vedanta, not-two, philosophy comes from the Upanishads. The study of Advaita philosophy along with meditation has been our practice for many years now, and they were the path for our teachers. The Brihadaranyaka Upanishad is reproduced in full on this site complete with our commentary on its philosophy.
The Brihadaranyaka Upanishad features prominently here because it is considered one of the greatest, both in size and in spiritual understanding. It is claimed that the Brihadaranyaka Upanishad especially, has ‘secret meaning’. Those secrets are the teachings of non-duality. But, those secret meanings are easily seen by those who read with an open heart and mind. We believe that The New Testament bible also contains subtle nonduality teaching. The same applies in the recently discovered Nag Hamardi scriptures containing the gospel of Thomas. We will also comment on those.

Why the use of subtlety or secrecy in the scriptures?

There is in the Brihadaranyaka Upanishad (ch2 section 5 verses 16-19) in the last 4 verses of that chapter a revealing story which explains the wisdom and need for some meanings to be hidden.

The story features the use of a horse’s head disguise. The use of a horse head has great significance in this Brihadaranyaka Upanishad itself. Ostensibly, this Upanishad is about an ancient Hindu horse sacrifice ritual. But, this story also reveals that the describing of that ritual is also to disguise the telling of the higher truth of Advaita, that their gods and deities are merely the peoples own projections. Their gods have no eternal true existence. The Absolute, Brahman, God, Consciousness alone exists.
The story in brief tells of The Rishi Dadhyac, the sage who after intense meditation has realised divine truth. The Asvins (Hindu twin deities), who were Knowledgeable about ritualistic beliefs, wanted to know the highest truth. The Rishi Dadhyac knew and could teach this truth but the Rishi was under a curse from the king of the gods Indra, that he must not teach this knowledge or Indra would become angry and cut his head off. But, the Asvins fitted Dadhyak with a horse head disguise so that he could teach the truth secretly. The meaning is, that within this whole Upanishad with its descriptions of rituals, gods and deities etc. the higher truth of non-duality is told but disguised. It is the people who worship gods of their own desiring that become angry at any challenge to their own beliefs. This should be easy to understand. They kill prophets, they killed Jesus. They kill those that challenge the comfortable long held beliefs and traditions of groups. This is the mind of duality, it fears challenges to its security.