Many non Hindus are question me. Why Hinduism allows Idol worship. Isn't it bad and unscientific. I answer them. Worship is self unscientific. The believe of existence of God is unscientific. Then how can you say that Idol worship is unscientific. Behind every activity, faith and think. There may be some scientific reasons. Similary, behind the idol worship by Hindus are purely scientific. It is not known to every one. In Hinduism, Rigved is the first book. In that book there is no idol worship. It only describes about nirakar (Unshape). Second is Samved, Third book is Yajurved. Even in second and third book, there is no description about idol worship. These books are prepared at different time as per the requirement of Society. Third book is Atharv bed is also called as Magical book. First time in this book, there was the description about the Sakar (Shape) brahm.
In ancient time, it was easy for educated and intellectual peoples to gain spiritual upliftment. Because they can believe in existence of god by listening, reading and generating their feeling that Nirakar (Unshaped) brahm exist. So they can worship god easily by there faith and get release from life death cycle. Then Saints and rishi think that how can we provide spiritual upliftment to general public. Because that time general public were mainly uneducated and having less knowledge. Even they cannot understand the concept by listening and practically it was complicated for rishis to make them understand about spirituality. Rishi describing about the Nirakar brahm ( unshaped) but they were not able memorize things and generate feeling for god. For general public, it was difficult to feel god. Then Rishis started thinking about the way how can they generate feeling in general public. They start to describes various quality of god. How god look like. For generation of universe, Rishi started to describe incarnation of God Brahma. Then they describe operation of universe as incarnation of god Vishnu and then for destruction of universe they started to describe God Rudra. Now general public was able generated various feeling for god. In Hindus there are 33 crore God and Goddesses. It means that God may have 33 crore quality or more. These feeling are activated one by one. Hindu doesn't believe in many god but one god with unlimited quality and feelings. This the scientific reason behind idol worship.
I can remeber a story about a famous saint who was invited by a king for dinner in his palace. That king was highly influence by the Brhama samaj. He was strongly disagree with the idol worship. Unknowingly, a debate has been started between the King and Saint. At last saint consider himself that he defeated. King become happy and ready to give anything as a gift to saint and allow him to do any thing in his palace. On that palace wall, a portrait was being hanged. That portrait was of late father of that king. Saint ordered his disciples to bring that portrait from wall and put that down and hit that with feet. The king become angary and replied to saint " how dare you" to disrespect my father. Then saint replied to king, your father is dead and it just a portrait how can I disrespect him. King said- yes, I know my father is dead but my feeling is attached with this portrait. Saint replied- similarly, idol is non living but the feeling of devotee is attached with idol as a god. King then understand the concept of idol worship and consider his self as he is defeated.
As you will see different idol of Hindu god and goddesses. Different types of feeling will be activated in mind. For Kali, it aggressive, violence, fear etc. For Vishnu it is smile, happy, peacefulness. For Shiva, it is sacrifice, strong, etc
Thanks
Jay Mahakaal