Hindu religion is based on Vedanta philosophy whose starting premise is that there is just one God (Brahman) who is eternal and without form or attributes. The immediate and instinctive question will be - why then we have all these gods and goddesses. Below I will try to answer that question briefly.
A religion is for the masses, common folks. Whereas the learned and ascetics can understand and assimilate the finer points of the philosophy, for the common man (or woman) it is extremely difficult to conceive of or concentrate on something abstract. So in order to bring the concept of God to the masses He had to be given a form.
The abstract God was the creator, the maintainer, and the destroyer all in one. These three aspects of God are perceived differently by the common man and therefore they were represented in the form of Brahma,Vishnu(NARAYAN) and Mahesh (Shiv). Thus emerged the three principal gods.
God was regarded as omnipotent, the Supreme power. Some people were attracted to this all pervasive power of God and wanted to worship Him as the power figure. The word for power in Sanskrit is ‘shakti’ which is feminine. The form for this aspect of God, therefore, had to be feminine. Now all kinds of power in the world can be divided into three basic categories - intellectual, material, and physical.
In keeping with this division people conceived of three godesses - , , and Parvati, who were conveniently paired with the three principal gods as their respective consorts. We thus got six gods and godesses each representing an aspect of the same one God.
In our day to day life we do not seem to have any problem in reconciling different aspects of a single personality. For example, a man is son to his parents, husband to his wife, father to his child all at the same time. Different aspects of God are viewed in the same way on a much larger and extended scale according to different perceptions. In an attempt to convey the teachings of Vedant to the masses through lucid stories Hindu mythology created more gods and godesses. Different names and attributes were given to some of the original six;new ones like were created. Vishnu’s incarnations Rama and Krishan came to be worshipped separately.
A distinguishing feature of Hinduism is that it is highly individualistic. One is free to worship God in whatever form and where ever one chooses. This led to the creation of a plethora of gods and godesses depending upon the individuals’ or groups’ inclinations and preferences. Scores of deities and their temples sprang all across the land. Yet in this multiplicity the central theme always persisted: every god or godess represents an aspect of the same one God.
There is no denying the fact that despite the central theme of one God the multifarious growth of deities had the deleterious effect of divisive sectarianism. Some of well-intentioned practices degenerated into social evils affecting the entire soceity. Coupled with the political fragmentation and upheavals these led to a steady deterioration of the social and political structure that continued for centuries before it could be stemmed. However, the basic framework of Hinduism has endured through the ages and Vedant remains as its firmbasis.