WHY IS GANESH OR ANY OTHER HINDU GOD IMMERSED AFTER PUJA?

Here is one explanation. There is a story behind the immersion of Ganesha. It is said that Mata Parvati wanted to go her maike (parents’ house). Lord Shiva allowed her to visit her parents. Just after one day after allowing Mata Parvati to visit her home, Lord Shiva sent Ganesha to bring her back to Kailash. On the day before the Ganesh Chaturthi, Mata Parvati comes to her parent's home to visit Her parents. The immersion of Ganesha is the sending back of Mother Parvati and Lord Ganesha to Kailash (their original home where Lord Shiva, Ganesh's father stays) as there is a route from Patala (bottom of the sea) to Kailash which denotes that the world is round.

One will have to understand that Hinduism is full of symbolism which only depicts a deeper meaning where every thing should not be taken literally as it is not a revealed religion like Islam. The ultimate Hindu belief lies in the Brahman, nirgun and nirakar, or something that is formless and invisible which is similar to the concept of Allah whose image or being cannot even be imagined.

But as Hinduism is very ancient and most people could not grasp the concept of a formless God, such images were necessary to make it easier for them to concentrate on a particular form of god. That is why Ganesh murtees (statues) or Durga Pratimas (statues) made of earth are immersed in rivers or seas after puja (worship) as they are symbols which like all creation must one day go back to where they all came from.

But the Pratimas made of stone or wood etc., and regularly worshiped in temples are not immersed as they are symbols of the permanent nature of the gods who represent various facets of the Supreme or Brahman (not to be confused with the god Brahma-the creator). In fact, as Hindus have 330 million gods and goddesses to take care of each and every need of theirs exclusively by a single god, they think that they are that many times luckier than those having only one god which makes them rather complacent about their religion.