What is the significance of “Aham Bramhasmi”?

Question

We Hindus believe that the Supreme lord (Shiva/Vishnu) exists. Then what does Aham Bramhamsi signify?

Answer 1

aham brahmasmi (I am Brahman) is one of the four mahavakyas -'great sayings' - from the Upanishads. It is from the Brhadaranyaka Upanishad I.iv.10. The verse reads (Swami Madhavananda translator):

This (self) was indeed Brahman in the beginning. It knew only Itself as, 'I am Brahman.' therefore It became all. And whosever among the gods knew It also became That; and the same with sages and men. The sage Vamadeva, while realising this (self) as That, knew, 'I was Manu and the sun.' And to this day whoever in like manner knows It as, 'I am Brahman,' becomes all this (universe). Even the gods cannot prevail against him, for he becomes their very self. While he who worships another god thinking, "He is one, and I am another,' does not know. He is like an animal to the gods. As many animals serve man, so does each man serve the gods. Even if one animal is taken away, it causes anguish, what should one say of many animals? Therefore it is not liked by them that men should know this.

And as the Astavakra Samhita 1.11 says (Swami Nityaswarupananda translator):

He who considers himself free is free indeed, and he who considers himself bound remains bound. 'As one thinks, so one becomes' is a popular saying in this world , and it is quite true.

If you say you are Brahman, you shall become Brahman; if you say you are a bound soul, you will remain a bound soul.

Answer 2

We Hindus believe that the supreme lord (Shiva/Vishnu) exists.

One must be careful when saying "we, the Hindus". Hinduism itself is constituted by several different belief systems that share a common origin in the Indian subcontinent. Some of them, like the Mimamsa school, maintain that there is a separate entity who can be worshipped through rituals; whereas others, like the Advaita Vedanta school established by Shankaracharya, claim that God/The Greater Truth is not separate from the soul/The Lesser Truth.

The Advaita school preaches mahavakyas such as aham brahmaasmi and tattvamasi. The word advaita itself means "not two" (a-dwaita).

Answer 3

Aham Brahmasmi is the anubhava/realization vakya out of 4 mahavakyas pointed out of Vedanta to depict the nature of Godhead. Words like Brahmasmi, Brahmin, Brahma, Brahmcharya are all linked with Br(a)hman(A as the first character of varnamala and OM(A+U+M)) which represents origin, oneness, aloneness from which the multiformed manifested creation emerged and realizing this vakya leads to Kaivalya. Just like a same form of Man becomes a Scholar, King, Businessman and worker playing their roles for functioning of society, similarly one Brahman alone has become Shiva, Vishnu, Shakti, Agni, Indra etc., to run the entire Nature. But just like a chemist with little knowledge cant treat an ill person, only a doctor undergoing lot of education and practice can, similarly for a novice spiritual aspirant identifying God as some third person, Shiva, Vishnu, Shakti etc., are different hence there had been conflicts over the name of God, even among Abrahamics religion, because of ignorance and also interest of people to spread their sect as majority with eventual goal of money and land but not spirituality. Bhakti of God is to establish faith over God but its not the end, how can a servant ever be happy and free/Mukta? Oneness, when Master/God and Servant/Man become one is the end. God is one Tapas/austerity.

Uttara Geeta

2.44. Therefore, the conviction that “I am Brahman“ is known to be the sole cause of emancipation (moksha) for great souls (mahatmas).

45. Two words bind and liberate the jivas respectively: the firm belief of ‘I‘ and ‘mine‘ holds fast and binds the jiva down, and the absence or want of the same liberates him from all bondage.

46. When the mind becomes free from all desires and passions, then only the idea of duality ceases. When there arises that state of Advaita feeling [all in One and One in all], there dwells the Supreme Foot of Brahman.

47. As a hungry person simply wastes his energy in vain when he strikes the air with blows, so too a reader of the Vedas and other shastras simply wastes his time and energy if, notwithstanding his study, he fails to realize “I am Brahman.“

No Brahmin was considered a real Brahmin until he realized vakya "Aham Brahmasmi" atleast in Satyuga when dharma prevailed and in reality Brahmin is not some caste but a state achieved by the scholars of Vedas and was the eventual goal for all the varnas thats why ancient kings Bharat, Rishabh etc., renounced their kingdoms to realize it.

' Janmanaa jayate shudraha sanskarad dvij ucchyate veda pathhatbhavet vipraha brahma janati brahmana ' (Atri Smriti, 141)

By birth everyone is a shudra. After following rituals, one becomes a dvij. After knowing the scriptures, one becomes a vipra and only after attaining the knowledge of brahman(God) does one becomes a brahmin.

But in Kaliyuga where materialism prevails and body as the only truth, the true purpose of Vedas and creation was forgotten among aristocrats and scholars of Vedas, hence Sannyassa/monkhood/Bhikshu(religious mendicant) was introduced within Kaliyuga starting from Buddha and Adi Shankaracharya where the realization of Brahman/Self became open to those alone who are interested in God-realization with living on alms as spirituality cant be forced upon anyone. This was explained by Yagyavalkya also, that a true knower of Brahman eventually becomes a religious mendicant.

Bridarayanka Upanishad: Section 5

3.5.1. Then Kahola, the son of Kuṣītaka, asked him. ‘Yājñavalkya,’ said he, ‘explain to me the Brahman that is immediate and direct—the self that is within all.’ ‘This is your self that is within all.’ ‘Which is within all, Yājñavalkya?’ ‘That which transcends hunger and thirst, grief, delusion, decay and death. Knowing this very Self the Brāhmaṇas renounce the desire for sons, for wealth and for the worlds, and lead a mendicant life. That which is the desire for sons is the desire for wealth, and that which is the desire for wealth is the desire for the worlds, for both these are but desires. Therefore the knower of Brahman, having known all about scholarship, should try to live upon that strength which comes of knowledge; having known all about this strength as well as scholarship, he becomes meditative; having known all about born meditativeness and its opposite, he becomes a knower of Brahman. How does that knower of Brahman behave? Howsoever he may behave, he is just such. Except this everything is perishable.’ Thereupon Kahola, the son of Kuṣītaka, kept silent.

Also in Uttara Geeta

3.13. Where the yogins stay for one second or even half a second, that place becomes sacred like Kurukshetra, Prayaga and Naimisharanya, because the thought of spirituality even for one brief second has a greater effect than one thousand million sacrifices.

16. O Arjuna, the yogin should not brood about, or concern himself with, his maintenance. If, however, such a thought is needed at all, then let him beg for alms simply maintain his body, and protect himself from cold by the clothes of charity. To him diamonds and stones, green vegetables and course rice, and all other objects in this world are of equal value

Actually these mahavakyas should not be listened by a common man who considers body as truth as they are misinterpreted, like "Aham Brahmsami" does not mean "Ego/Body is God" for a bound soul., hence for them Dvaita Bhakti was introduced parallely. Its the Aatma, hence "Ayam Aatma Brahman-My soul is God" is its preceding Mahavakya.

Manu Smriti Chapter 8: 272. If Shudra(once-born man) arrogantly teaches Brahmanas their duty, the king shall cause hot oil to be poured into his mouth and into his ears.

For example there is a story of shudra Shambuka killed by Rama, for trying to do Tapas(nature of Brahman) because he was following duties of other varna Brahmin but not of his own.

Despair and Hope in Age of Kaliyuga

(2) Among the people of the age of Kali all one attains by good birth, behavior and qualities will be wealth while material power will be the only factor determining what is just and reasonable. (3) Relations between men and women will be based upon sensual pleasure, business will be ruled by deceit, masculinity and femininity are there for sexual attraction and a sacred thread will suffice to be considered learned. (4) External marks only determine someone's spiritual status and constitute the basis for mutual exchanges, because of a lack of funds one is less credible and scholarship consists of word jugglery.

But in Kaliyuga when confused rigid castes are functioning and hypocrisy, money and power is given more importance than truth, Puranas/Bhakti is given more importance than Vedanta/Gyan because of Tamas among people of Kaliyuga where default consciousness is in Body but not soul, with Majority of mankind as Mleccha(80% world population non-Vedic or atheist). Thats why Vedas and Vedanta is open to entire world as original people who were given the duty of realizing Brahman are not interested in it, Godhead should be given to those who value it but not misuse it to show actionless birth based dominance. Hence, people come across Vedanta and get confused with current dualistic mainstream Hinduism.