Upanishads are not old in the sense that they are outdated, ineffective and stale. It considers the Vedas to be eternal, timeless and contemporaneous with Brahman. Brahman, associated with maya, also the cause is saguna Brahman, also called Isvara. That is, the totality of human existence: all thought and love, and hopes and desires, all perceptions of afterlife and governance of the present, all fears and hatred bound as one with love and trust and death.
1) In Hinduism, Brahman is "the unchanging reality amidst and beyond the world", which "cannot be exactly defined". For thought processes there is active information serving as a link between our two material and spiritual sides (The age-old mind-body issue).
Atman-Brahman is a product of this psychedeliс search. At this stage, what remains is the Absolute Consciousness of Brahman and we become one with it. Religion believes in God the Father or Jesus, or Allah, or Brahman, or Tao. Many famous Indians are Brahmans. The Ultimate Truth is expressed as Nirguna Brahman, or God without form, or God without personal attributes.
In so far as he understands the three-quarters of speech (i.e. the Veda
) that is not articulated, the brahman is regarded as the ‘mind' ( manas ) of the sacrifice. All these names and forms are illusory, like a dream What Brahman is cannot be described. But the same was not true of the formless Nirguna Brahman, beyond duality and activity.
God is Saguna Brahman, or Brahman with attributes. But there must be an absolute reality at the base of this consciousness, otherwise we would not have had consciousness. Even after intellectually convinced that the Self is Brahman by Vairãgya, Åšravana and manana, seeker still finds it difficult to transform.