The idea of Brahman is from the Upanishads. The etymology of the word is not very clear but it refers to a Universal Spirit or substratum that is the origin and end of everything. It also forms the core of our being.
The Gnostic monad, The En soph of the Kabbala, The Dharmakaya of Buddhism, The Tao of Taoism, Allah of Islam.....all are similar ideas.
The word itself is not important. It is a philosophical idea. Because it is from the scriptures... it could give a religious or mystical feel. But it is not very different from the idea in psychology of a common unconscious mind that envelops everything....or panpsychism/cosmopsychism. Jung advocated it.
As we try to understand the idea of the unconscious mind more and more we could understand our basic nature a little better.
