I always remember one line of Sethji (Shri Jaydayalji Goyandka, the founder of Gita Press). He said – 'The one who says I have realized (attained God), the one who says I have not, the on who says I do not know whether I have or not – all three have not realized (attained God).' "
If no one among the three groups has realized God, then who has realized God? Kindly explain.
This is a very beautiful concept that is originally found in the Kena Upanishad.
The translation is as follows
2.2 The disciple said: I do not think I know It(Brahman) well, nor do I think I do not know It. He among us who knows the meaning of "Neither do I not know, nor do I know"—knows Brahman.
2.3 He by whom Brahman is not known, knows It; he by whom It is known, knows It not. It is not known by those who know It; It is known by those who do not know It.
Basically the knowledge "aham brahmasmi" is the knowledge about one's true self, it is a knowledge of right self-identity. As even this knowledge arises, the false superimposition called the Ego vanishes.
In other words, self-knowledge is not knowledge of something, like knowledge of a pot or knowledge of a flower, but is a subjective knowledge of the real "I" - sat-chit-ananda.
So if i say i know brahman, it means that there are two entities - i and brahman. that how can i and brahman be the same? only when it is realized firmy as one's own swarupa and not as a "thing" to be known can one says "he knows" or "he is realized"
Now let us take the three groups mentioned by the revered Giyandka-ji.
The one who does not know whether he knows or does not know is clearly ignorant of what this knowledge is. If you ask him do you know who you are or who is Ishwara he has no clue.
The one who says he is realized also does not know. This is because for a reality there was never a time when he was not realized. Bondage and its release are both fictitious from his standpoint - the one who was bound and the one who obtained release were both the very same imposter - the ego, which meets its death upon realization. So there is no "i"-sense that will say i am realized.
The one who says "i am not realized" is ascribing a reality to his bondage. Under the firm sway of avidya, he is sure that he does not know nor does he possess the means to know the Divine which is ever his true nature, right at this very moment.