[Advaita-l] Knowledge of Brahman

[kuntimaddi sadananda]

Harshji - PraNAms

Your question are fundamental and it requires the detailed study of Advaita Vedanta under a sampradaya teacher. Otherwise these contradictions remain without having a clear vision of Advaita 

I am going to provide my understanding of basics but for deeper understanding, one has to study under a competent teacher. 

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You said:

We get the moksha through the knowledge of brahman according to vedas, but
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Not really. Shankara says in Vivekachudamani– brahmaa aatma aikya bodhena mokshaH siddhyati na anyathaa.  Thus moksha comes only by mahaavakya vichaara. Hence Advaita Vedanta involves 1. Brahma satyam, 2. Jagat mithyaa 3. JeevaH brahma eva, na aparaH. All the three aspects are involved. 
A clear understanding of the above will resolve the rest of your questions. 
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1) Infinite cannot be known by finite.
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True – from infinite there are no finites for it to be known. Hence Brahman does not have to study Vedanta; and cannot know and in fact need not have to know also, since it is Brahman which is ekam eva adviteeyam. Hence Vedanta study is not Brahman.  Since the question is asked not by Brahman but by jeeva who thinks he is finite entity, he needs to do mahaavaakya vichaara to recognize that He is really Brahman; and therefore he also need not have to know anything else. However, until he understands that he is Brahman, he has a notion that he is finite and to remove that notion he needs to do Vedanta vichaara. Since he is a jeeva is only a notion and not a fact, proper inquiry of the fact will remove his misconception. Hence it is not finite trying to know infinite; but it is clear recognition that I am not finite but infinite already. The fact is every jeeva is looking for happiness, day in and day out and life after life, without recognizing the happiness is his intrinsic nature.  Since limitless alone is happiness, he has to recognize that he is really infinite and not limited BMI. The notion that I am finite is in the mind only, and not in the aatma. Hence the study of Vedanta is for that mind who has wrong notions about itself and the self. 
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2)Nirguna can never be known ,because suguna can be known through suguna's
guna,but nirguna can never be known,because he is attribute less.
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True – only infinite is nirguna since it is infinite. Only objects which are finite have gunas. Hence Brahman being infinite has no gunas since Brahman is not object. Also subject, I also has no gunas since subject I cannot be objectified. Hence the mahavaakyas also follow. Hence subject I not the Brahman can be known as subject. Let me give you a simple example. Suppose you are sitting a pitch dark room. I ask – Q. Sir, is there a chair there in that room? 
You can only answer, that it is too dark and you cannot see anything. Chair may or may not be there as you cannot see. I need a light to see things. 
Q. Sir, how do you know it is dark since you said you cannot see anything? 
A. Oh! That I can see! I can see that I cannot see! – In essence I can see that is dark without any light – in fact I do not need light to see darkness or even ignorance since I know that I do not know if there is a chair or not. 
Q. Sir, Are you there in the room since you said it is too dark that you cannot see anything? 
A. Of course I know I am there. I do not need light to see myself as I am self-revealing to myself! I am aprameyam not an object (with gunas) for me to see or to know! I am self-existing and self-conscious entity. 
Vedanta only says that existent-conscious entity that I am is Brahman – aprameyam not an object to know. Hence one cannot know Brahman. However with proper use of the words, in the hands of a teacher, one can drop the wrong notions about oneself and claim one glory.  

3)Nirguna cannot have knowledge. As knowledge is also a guna.
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Yes. Brahman does not have knowledge – Knowledge you are discussing is objective knowledge where there is pramaata-prameyam and pramaana. Brahman is jnaana swaruupam – satyam, jnaanam anantam brahma. Pure knowledge cannot be defined. Epistemologically only knowledge of x or y can be defined where x or y are object – not Brahman or true subject, I. 
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So,we never get knowledge of brahman,if brahman is nirguna, in other words
we never get moksha if brahman is nirguna.
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First part is right not the second part. Moksha is defined above – it is just dropping wrong notions about oneself. 
If I may suggest (not as advertisement) you can listen to the talks on Introduction to Vedanta or Advanced Vedanta series on yu-tube under Acharya Sadaji. Many of these misconceptions can be removed. 
Hope this helps
Hari Om!
Sadananda
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