Image worship crept imperceptibly in Hindu religion. It was later sanctioned in religious scriptures. Image were considered as personification and god head. Rituals for worship of images were also prescribed in great detail.
Uninitiated and ill informed persons may believe that a deity is nothing more than an idol, so it is not worthy of any attention. However the deities are connected with sadhana (extraordinary power of mind). They are powerful god heads. The conception of god head is spiritual or psychic matter. A very famous Hindu saint has said that when ‘Zero’ is depicted than why not all powerful god should be represented and worshipped.
Thus idol worship is an important feature of the Hindu religion. Idolatory is prohibited in Brahma samaj and Arya Samaj founded and fostered in the 19th century by Raja Ram Mohan Roy and Swami Dayanand Saraswati respectively. These two cults reach the worship of the self. However all Hindus believed in Brahma, the supreme Being.
When a worshipper uses a concrete symbol or image for concentration it is called saguna, form of worship. In nirguna, mind is fixed without any physical symbol. Nirguna form of worship is a higher step by drawing the mind inward without the help of any physical symbol.