In advaita oneness one can invent the ideal God, but no one ever has proof of the existence of any kind of God, whether Personal God or Creator God. For satchitananda one must have invented for oneself the ideal God. Then Advaita is realised and you are it. Tat Tvam Asi.
So what is the ideal concept of God? God is Truth and Truth is God. Then one just goes about accommodating the truth, and this definition of advaita is to be called Satya-advaita. If one chooses or invents any other idea of God that does not generate Ananda and so is not Advaita. It is oneness with a God polluted with untruths, so delusional advaita. So Advaita Vedanta is Satya-advaita Vedanta.
Sat-chit-ananda is Truth-awareness-bliss.
Attachments are impurities in the mind that generate delusional thoughts instead of the awareness of Reality.
Brahma is the Hindu term for Physical Energy, the Reality, that manifestats as the universe that we see and experience. Within this Reality we invent our Gods as Personal Entities, the supreme one being the ideal God that harmonious with Brahma. That is Advaita Vedanta, and the path to this ideal God is the truth path, hence to be known as satya-advaita yoga.
All that exists is Brahma: I am Brahma, rock is Brahma, tree is Brahma, sun is Brahma; all Physical Energy.
Brahma Satya Jagat mithhya is true because the cosmos is a manifestation of Brahma (Physical Energy).
So long as the mind is there with thoughts, beliefs and attachments, atman (soul) is present. When the mind disappears only Brahma remains.
When the mind has gone for good awareness prevails and one is spontaneous in actions because one has truth as Brahma.