Why do we Hindus worship so many Gods while the other religions worship only one God?
Story to explain how the same God can take on different and forms names
A student asked his teacher, "How can the same God sometimes be Vishnu or Shiva or the Mother Goddess, or a God in another religion?" The teacher asked the student to come to his home the next day. In the meantime, the teacher bought lots of different shaped moulds for making ice in his freezer. Some moulds were like cubes, some were round and some were like stars. The next day when the student arrived, the teacher took out all the moulds from the freezer and from each, he took out differently shaped blocks of ice. Some looked like cubes, some like round balls, and some looked like stars. He then placed all of them in front of his student and asked if they were all different. The student said, "Yes."
The teacher then explained, Even though they look different, and you call them by different names like round, cube and star-shaped, they are really the same. They are all made out of water. The same water becomes frozen into different shapes. In the same way, the same God is called by different names. Some Hindus call God Vishnu, some call him Shiva, some like to think of God as the Mother Goddess. People of other religions have their own different names for God.
This story explains how Hindus think of the same one God in different ways. The same God is given different names by other religions too. Even though the names and forms of God are different, it is still the same God that all religions adore.
Reference: Primary Hinduism by Seeta Lakhani (Ch.6, 'Can we see God?', p.29)