When God is one then why do we need to worship so many God and Goddesses?


You don’t need to; it is not a compulsion to worship so many God and Goddesses. It is the One God that you worship in so many forms.

One ray of light has so many colors. There are seven primary colours in one ray of light. In the same way, the same Parambrahma is worshiped at times as Ganesha, at times as Devi, at times as some other form.