That is a mis-representation of Hinduism and needs to be addressed.
1. Hinduism is not monotheism. The majority is polytheist.
a. When they said 'Ekam sat, vipra bahudha vadanti', they meant Indian religions (Hinduism, Buddhism, Jainism, and Sikhism) which share our world view and certainly did not mean Judaism, Christianity, and Islam, which say 'I am your Lord, the God, and you must not worship any else'.
b. 'Ekam eva advitiyam' That is NOT 'I, alone, am' (find me the word which means 'I'). That is "(There is) only one, no second". And what is that? It includes everything in the universe, all people, animals, vegetation, water, air, rocks, to exclude anything is blasphemy.
2. Not everybody accepts existence of God/Gods. I am an atheist. What some sections of Hindus accept is universal presence of some entity, it may be a impersonal God or it may not be. Write the full name - Isavasya Upanishad is one of the many, it is not Hinduism's Bible or Qur'an.
a. "Repentance is a process through which we discover this truth.": No, truth is discovered by study and research. How would repentance give any idea about Higg's Boson. Repentance is only for the guilty. Is that because Adam ate an apple given by Eve?
3. I do not believe in creation. The view I follow is that the perceived in not the truth, it is only a mental construct. There is no creation.
Kindly explain what should I understand by manifestation?
'Sarvam eitad Brahma, sarvam kalvidam Brahma' means all things here are constituted of Brahman (and Brahman not necessarily being a God but just the substrate, like a chair as well as a table may be made of wood). Do Christianity or Islam accept that or even something close to it?
4. 'Prajnanam Brahma'. It is from one of the oldest Upanishads when people knew little, and is, IMHO, not correct. Consciousness is a temporary thing, a state of mind, which comes and goes with the body. What proves that the universe is constituted by it? What proves that there is a universal consciousness?
5. 'Aham Brahma asmi': I am Brahman, my true self is God; (Now do not make Brahman into a God, some people do not take it in that sense. And even if they take Brahman as the God, it is impersonal, uninvolved.)
Jesus said I am the light of the world; my true self is the light of the world. I am the way, the truth and the life.
Fine, if Jesus said that he is the light of the world; going by the Hindu belief, all people are the light of the world, the way, the truth and the life. Then, us too, are the way, the truth and the life. What is, then, so special about Jesus?
6. 'Tat tvam asi': you are that brahman, you are Brahman or your true self is God or Brahman. (Now do not make Brahman .. it is impersonal, uninvolved.)
Jesus said, you are the light of the world. Your true self or real self is the light of the world.
Did he say that? Where? Kindly give reference. Only the light of the world, and not the way, the truth and the life (see #5).
7. 'Ayam atma Brahma': This 'self' (atman) is Brahman. Atman, the ground of the human consciousness is one with the Brahman, the ground of the universe.
The ground of human consciousness is the brain. Like everything else, brain also is constituted of Brahman (whatever it may be).
8. 'God is Pursusothama: the Upanishads present God as impersonal. The Bhagavat Gita adds the element of personality to God. God is supreme person, God is love.'
The first question is whether there is any God? Brahman remains undefined, the only thing we can say about it according to Hinduism is that it is 'Neti, neti' (Not this, not that). Upanishads do present an impersonal entity but never beyond that. There are many ways to understand Bhagavat Geeta. If Krishna is Brahman, then he cannot be termed as a person, that will be a severe limitation and wrong. God, at least, Brahman, can neither be love nor hate, since it is impersonal.
'For Jesus Christ also God is a supreme person, purusothama. This personality of God transcends all human categories. God is unconditional love. God's love is like the Sun which gives light to all unconditinally.'
Brahman is not a person, therefore, it cannot be termed as 'purushottama'. Many Hindus do not believe in Christian kind of God. It God transcemd all human categories, then it is futile to terms it as loving or hating, because these are human emotions. If God is love, then why is there evil in the world? Why is there a hell and that too eternal? Why did God destroy Sodom and Gomorrah? Why did God ask Moses to kill everyone engaged in idolatry? And why did Jesus curse the cities? That means that even if there is a God, there cannot be 'unconditional love'.
9. 'Love is wisdom manifesting in love. The Upanishads emphasize on the path of wisdom. The Bhagavat Gita integrates many spiritual paths, particularly Jnana, Bhakti and Action. In the Bhagavat Gita Love is wisdom manifesting in action. it is the marriage of wisdom and action in Love. Wisdom is the experience of oneness with God. Krishna represents wisdom. Arjuna represents action.
For Jesus Christ Love is wisdom manifesting in action. Wisdom is his oneness with God. All his actions come from that wisdom. Hence Love is wisdom manifesting in action. It is the union of the love of God and love of neighbour.
Jesus Christ both God and human: at one level he is one with God. He is Krishna. In another level he is a human being, he is Arjuna. He says 'thy will be done'. he is fully human and fully divine.'
Love is wisdom, but only up to a limit. There cannot be 'unconditional love'. When one is faced with 'adharma', one has to take appropriate action. That is what Krishna advised Arjuna, that he should not hesitate to get into a war if 'dharma' demands it even if those opposing him were his own relations. This is true for Jesus also, one can say 'love when it is convenient'. I agree with oneness with Brahman, differences being illusions. One can love a neighbor if the neighbor is worth it. Can love al-Quaeda killers be loved? Not just Jesus, I too, am Brahman as well as Human. You too are that and so is the dog in the street. That is what is oneness with Brahman. Brahman does not have a will, because Brahman does not have any desires, not even to be worshiped, one thing that the Abrahamic God is after. Arjuna was asked to fulfill his dharma and not the will of a God.
This view of Hinduism is not that of a Hindu. Talk about Christianity. Why talk about something without understanding it very well. As you do not feel to go into the question of reincarnation now, I will leave it at that. Whenever ready to discuss it, we can meet again. Best regards,