I have spent good time understanding what is Atma or Self. Scriptures say Self is in every being and every being is in Self.
However if someone asks me "Who am I?" then what should be my response?
Or similarly if I ask you "Who are you?" then what will you say?
Atman. You've already said you've spent good time in understanding what is Atman or the self and the answer of "Who am I?" is already hidden in that thing.
Now, since you've started to learn spiritual concepts like Atman, the question "According to Hinduism" would be more suitable if you ask "According to <specific philosophy like Vedanta>" Because Atman immediately refers to the self of being, the more subtle meaning of Atman and it's interpretation is now important to know & understand which can be specific (or say varies) according to particular philosophy.
The question "Who am I?" is considered to be very important and essential in the self inquiry and the knowledge attained by this is called self-realization (Atma Jnana). Let me make it clear to you that when you say Atman, it can have two different meanings 1. Jivatma (individual soul), 2. Paramatma (supreme soul). Now in Vedanta (one of the six Astika Darshan i.e Hindu Philosophy), there are several sub classifications like Advaita, Vishishtadvaita etc. which interprets the relationship between individual soul and supreme soul differently.
In general, if a spiritual person ask you "Who are you?" you can say based on what Adi Shankaracharya chanted (which is known as Atma Shatkam or nirvANa ShaTkam) while the similar question asked him. (Note that this is more suitable with Advaita):
Quoting only English translation from Sanskrit documents:
I am not the intellect, ego, mind .
Neither am I hearing, taste, smell, sight . Nor am I space, earth, light, air, field of consciousness. I am the pure consciousness of bliss - I am Shiva . Shiva am I . .. 1..I am not prana, nor the five vital forces. I am not the seven elements of the body, or the five sheaths forming the body. I am not the organ of speech, hand, foot, the organ of procreation or excretion. I am the pure consciousness of bliss - I am Shiva, I am Shiva . .. 2..
I have nor attachment or aversion; No greed or delusion, not envy or vain; duty, acquisition, desire nor liberation do I aspire - since I am the embodiment of knowledge and bliss - I am Shiva, I am Shiva .. 3..
I am neither virtue nor vice, Pleasure or pain that is experienced, no, no; A chant, a holy place, a scripture nor the sacrificial fire; I am neither the enjoyment, enjoyable nor the enjoyer I am the embodiment of knowledge and bliss - I am Shiva, I am Shiva .. 4..
There is no death or fear, No one to distinguished by class or caste No father, no mother, no birth at all; No friend, no kith or kin, guru or shishya - I am the embodiment of knowledge and bliss - I am Shiva, I am Shiva .. 5..
I am Changeless, formless, enveloping all, Untouched by senses, I am omnipresent, Unfathomable, I am beyond freedom - I am the embodiment of knowledge and bliss - I am Shiva, I am Shiva .. 6..
Let me tell in the brief that the answer to Who am I is Ultimate Reality called Brahman in absolute level according to Advaita, however the answer would be just individual self which has qualified non-dualism with Brahman according to Vishishtadvaita.
You can look for some books/works written by Acharyas or spiritual scholars like Adi Shankaracharya, Ramana Maharshi, Swami Vivekananda etc. Knowing the attributes of Atman and Brahman can help you. e.g Who am I?
Also note that the path/journey of spirituality is not speedy i.e you should not hurry to understand various philosophies in short time. It's recommended to learn/read gradually with great patience. In this way your intellect will develop to understand such subtle and spiritual concepts.
I am posting Sri Ramakrishna's discussion about the nature of one's 'I'. Usually one confuses one's 'I' with the ego.
Think of Brahman, Existence-Knowledge-Bliss Absolute, as a shoreless ocean. Through the cooling influence as it were, of the bhakta's love, the water has frozen at places into blocks of ice. In other words, God now and then assumes various forms for His lovers and reveals Himself to them as a Person. But with the rising of the sun of knowledge, the blocks of ice melt. Then one doesn't feel any more that God is a Person, nor does one see God's forms. What He is can not be described. Who will describe Him? He who would do so disappears. He cannot find his 'I' anymore.
If one analyzes oneself, one doesn't find any such thing as 'I'. Take an onion, for instance. First of all peel off the red outer skin; then you find thick white skins. Peel these off one after the other, and you won't find anything inside.
In that state a man no longer finds the existence of his ego. And who is there left to seek it? Who can describe how he feels in that state - in his own Pure Consciousness - about the real nature of Brahman? There is a sign of Perfect Knowledge. Man becomes silent when It is attained. Then the 'I', which may be likened to the salt doll, melts in the ocean of Existence-Knowledge-Bliss Absolute and becomes one with It. Not the slightest distinction is left.
[The Gospel of Sri Ramakrishna, October 28, 1882]
If 'I' as the ego vanishes then what is our 'I'?
The younger Naren:"Sir, have we any free will?"
Sri Ramakrishna:"Just try to find out who this 'I' is. While you are searching for 'I'. 'He' comes out. 'I am the machine and He is the operator.' You have heard of a mechanical toy that goes into a store with a letter in its hand. You are like that toy. God alone is the Doer. Do your duties in the world as if you were the doer, but knowing all the time that God alone is the Doer and you are the instrument."
The Gospel of Sri Ramakrishna, July 14, 1885
Our 'I' is really the Atman.
There is one word of caution here.
But in the Kaliyuga, man, being totally dependent on food for life, cannot altogether shake off the idea that he is the body. In this state of mind it is not proper for him to say, 'I am He'. When a man does all sorts of worldly things, he should not say,'I am Brahman'. Those who cannot give up attachment to worldly things and who find no means to shake off the feeling of 'I', should rather cherish the idea, 'I am God's servant; I am His devotee'. One can also realize God by following the path of devotion.
The Gospel of Sri Ramakrishna, August 5, 1882
There are two more ways to understand Atman or the Self. It helped me a lot in understanding Atman.
That which cannot be expressed by speech, but by which speech is expressed—That alone know as Brahman and not that which people here worship.
That which cannot be apprehended by the mind, but by which, they say, the mind is apprehended—That alone know as Brahman and not that which people here worship.
That which cannot be perceived by the eye, but by which the eye is perceived—That alone know as Brahman and not that which people here worship.
That which cannot he heard by the ear, but by which the hearing is perceived—That alone know as Brahman and not that which people here worship.
‘What smell does not reveal, but what reveals smell— know thou That alone as Brahman, and not this that people worship here.’
2.From Katha Upanishad (Verse 1.3.3)
- Know the âtman as the lord of the chariot, the body as only the chariot, know also intelligence as the driver; know the minds as the reins.
- The senses, they say, are the horses; the objects which they perceive, the way; the âtman, the senses and the mind combined, the intelligent call the enjoyer.
As with many questions, on this particular question you will get different answers, and sometimes even contradictory answers, because different Hindu traditions (sampradayas) have different explanations of those things in their systems of Vedanta. Those who follow dualistic systems of Vedanta, such as those of Vaishnavas, will say that there are two souls (atmas) in the body of each living being, namely Supersoul (paramatma) and individual self or jiva soul (jivatma). So the answer to your question is that of those two souls in our body we are only jivatma soul, but we are not the other soul called paramatma.
Vaishnava conclusion is that the individual living entity (jivatma) is eternally different from the Supreme Soul or Supersoul (paramatma) who exists as Supreme God:
dvā suparṇā sayujā sakhāyā samānaṃ vṛkṣaṃ pariṣasvajāte tayor anyaḥ pippalaṃ svādv atty anaśnann anyo abhicākaśīti
"The individual spirit-soul (jivatma) and the Supersoul (paramatma), are like two friendly birds sitting on the same tree (body). One of the birds (the individual atomic jiva soul or jivatma) is eating the fruit of the tree (the sense-gratification afforded to the material body), and the other bird (the Supersoul or paramatma) is not trying to eat these fruits, but is simply watching His friend (jivatma)." (Svetasvatara Upanishad 4.6)
Here it is clearly pronounced the difference: "two friendly birds" and also "the other bird"!
Sanskrit: dvā suparṇā -- two birds; anyaḥ -- the other.
Two birds (two souls) are never just one bird (ie they are never one and the same soul!), and also the verse clearly says "the other bird"! which means that the verse is also talking about the other soul and not just about one soul. Thus, the difference between the two souls is established in this verse of the Svetasvatara Upanishad 4.6.
According to the Vaishnavas this difference between the two souls, jiva and paramatma, cannot be denied. This difference is real and eternal.
The same is also stated in the Mundaka Upanishad 3.1.1:
"Two birds, inseparable friends, cling to the same tree. One of them eats the sweet fruit, the other looks on without eating."
In those verses we also see that one bird (jivatma) is eating the consequences of karma "one of them eats" says the verse, while the other bird (paramatma) is not participating in karmic results because the verses say "the other looks on without eating". From this we also see that there is the difference between the two souls because it would be absurd to explain those verses that they teach about only one soul, namely it would be absurd to think that one and the same soul simultaneously is affected by karma and is not affected by karma. The only logical explanation is that two different souls exist in the body, one is subject to karma, and the other is not subject to karma. Obviously we are not that other soul (paramatma) who is not subject to karma.
You are just the jivatma. You are not the heart, mind, feelings, consciousness, senses and body. You are not the paramatma as well. You are the witness of your individual feelings, thoughts and body. You are the jivatma who is feeling, thinking, can see and hear, etc. But all that you can do only connected with your own body. You can not witness the feelings, thoughts, and bodies of other living beings. But paramatma can do even that, he can witness everything, all the bodies, all the thoughts, etc, of all the living beings.
Jivatma is situated only in one body, namely in his own body, but paramatma is situated in all the bodies of all the living beings.
Here is the verse about one God who is paramatma dwelling in all beings, all-pervading Lord who is the witness watching over all the jivas or living beings (jivatmas) and watching over all their works or activities (karma):
eko devaḥ sarva-bhūteṣu gūḍhaḥ sarva-vyāpī sarva-bhūtāntarātmā karmādhyakṣaḥ sarva-bhūtādhivāsaḥ sākṣī cetā kevalo nirguṇaś ca
"He is the one God, hidden in all beings, all-pervading, the self within all beings, watching over all works, dwelling in all beings, the witness, the perceiver, the only one, free from qualities." (Svetasvatara Upanishad 6.11)
Thus we know that paramatma is dwelling in all beings, and thus He is witnessing and watching over all the jivatmas. Thus He is the witness of everything, ie of all the bodies, all the thoughts, deeds, etc, of all the living beings.
