Question Part 1: God is one, the Supreme being (Lord Shiva, Lord Krishna, Lord Vishnu, Lord Rama and so on). All are the names of the supreme being who is not a human, but energy.
It is incorrect to say that the Supreme is just energy. He possesses both form as well as energy. In the Srimad Bhagavatam 1.2.11 it says:
vadanti tat tattva-vidas
tattvam yaj jñanam advayam
bhagavan iti sabdyate
Learned transcendentalists who know the Absolute Truth call this
nondual substance Brahman, Paramatma or Bhagavan.
So the Absolute Truth consists of Bhagavan (a form that is transcendental unlike a material form that we are used to), Paramatma ( a form that resides in every one's hearts, along with the Jiva) and Brahman (all pervading aspect that you refer as energy)
In Bhagavad Gita, Lord Krishna says Brahman is subordinate to Him.
brahmano hi pratisthaham
sasvatasya ca dharmasya
And I am the basis of the impersonal Brahman, which is immortal,
imperishable and eternal and is the constitutional position of
In the same Bhagavad Gita 15.15, Lord Krishna says He is the paramatma in everyone's heart:
sarvasya caham hrdi sannivisto
mattah smrtir jñanam apohanam ca
vedais ca sarvair aham eva vedyo
vedanta-krd veda-vid eva caham
I am seated in everyone’s heart, and from Me come remembrance,
knowledge and forgetfulness. By all the Vedas, I am to be known.
Indeed, I am the compiler of Vedanta, and I am the knower of the
And as I discuss in my answer to another question here, the Supreme has a personality and Lord Krishna is that Supreme Person.
Question Part 2: Now, can I put my own name for that Supreme being and my own symbol for worshiping him? Sometimes, I represent him as space. Will doing so give moksha, fulfill material desires etc?
I doesn't mean to represent them as demigods like Sun, Moon or gods of other religions. But in an entirely new name, a new representation (not Shiva Linga, not the way Lord Vishnu is represented). But entirely new.
You can do what ever you want. Jiva has free will to act as he/she wishes but then one has to face the results of his/her own activities. You will not get moksa or get material desires fulfilled by such means. If you are making an imaginary form that doesn't exist, how can you expect that imaginary form to bestow anything upon you? It is illogical and we do not see any evidence of any one attaining moksa by such means in the realm of Vedic scriptures. A perspective from Srimad Bhagavatam follows. Depending on the degree of advancement, those who are materially absorbed are recommended to worship the Virat rupa, a form of Vishnu that represents the whole universe. You can read that from Srimad Bhagavatam here
Those who are more advanced are recommended to meditate on the four armed form of Vishnu who resides in every one's heart as Paramatma. This is found in the Srimad Bhagavatam in the next chapter here
Now those who are devotees, who accept the personal form of the Lord based on the sastra(sciptures) and sadhus(saints) worship deity forms, arca vigraha. These should not be of imaginary people, but they should be made as a replica of the form of the Lord as described in the scriptures. You see an example of this kind in Srimad Bhagavatam 4.2.17, in regards to Dhruva Maharaja's worship:
tasyam visuddha-karanah siva-var vigahya
baddhvasanam jita-marun manasahrtaksah
sthule dadhara bhagavat-pratirupa etad
dhyayams tad avyavahito vyasrjat samadhau
In Badarikasrama Dhruva Maharaja’s senses became completely purified
because he bathed regularly in the crystal-clear, purified water. He
fixed his sitting position and by yogic practice controlled the
breathing process and the air of life; in this way his senses were
completely withdrawn. Then he concentrated his mind on the
arca-vigraha form of the Lord, which is the exact replica of the Lord
and, thus meditating upon Him, entered into complete trance.
'sthule dadhara bhagavat-pratirupa' indicates he worshiped a physical form(sthula), which is made after the form of the Supreme Lord (bhagavat-pratirupe). This is the proper form of worship and not as per our own imaginations.
Question Part 3: I feel one must Love the Supreme Being but not his name or the way he is represented or the gifts he is giving. However, I still agree that the way they have been represented will induce bhakti but still, I am curious to know the answer imagining them in entirely new way.
As per the scriptural citations above we must worship in authorized ways only. Regarding His name, the names of the Lord are not material. They have full potency and infact the best means, in this age, for moksa and eternal service in Vaikhunta. The glories of the holy names are unlimted and here are a couple of references: (1)Some citations from various scriptures and (2)Wonderful story of a fallen Brahmana, Ajamila, being protected by chanting the holy name of Narayana, even indvartenty (the story continues in other chapters)
If you are serious about understanding Absolute Truth and attain moksa, Vedic epistemology of all schools of thought is through a guru and scripture and not by once imagination.
Note: Unreferenced citations from Vedabase.com