There is a nice story on Akbar and Birbal (historical characters) which related to proving god is one. Lets have a nice read !
Akbar the great Mughal emperor used to discuss many religious topics with his wise minister Birbal. On one occasion, Akbar asked, "Birbal, we worship Allah. The Christians pray to Jesus. But why do Hindus have so many GODS and GODDESSES? Birbal quoted the Veda & said, you’re Majesty, God is one. It is we who call him by many names. "
"You should prove it. otherwise I won't accept your argument", Akbar said decisively."I shall prove it now" said clever Birbal. He then clapped his hands and called a palace servant, pointing to the cloth wound around his head, he asked the servant, "what is this?'
The Servant replied, "Head gear, Sir!" Birbal sent him away .He then removed his head cloth and unfolded the cloth. He covered himself with it. He called another bearer of the court and asked him "What is this?”The bearer said "it is a Shawl, sir".
Birbal sent him away too. He then removed the cloth the cloth and wound it around his waist. He called a watchman and asked him, what is this?”He replied,"This is a Dhoti, Sir".
Birbal then turned to the emperor and said, you have seen sir, how the same piece of cloth was called head-gear by one man, Shawl by the second and dhoti by the third. The name of an article changes according to its place and application. Similarly water is called a cloud, stream & ice depending upon its external appearance, its material content being the same!
God Similarly is one! His names are many, changing with location and use!" Akbar was satisfied with the Birbal's wise reply.