The following is an article by Bhaktin Reena.
Hindus say they don't consider idols their gods. They only use a form to concentrate their mind in prayer. Why do people from other religions still consider it idol worship?
Such Hindus are ignorant about the divine form of the Lord and cannot understand the mystery behind deity worship. They belong to the category of spiritualists known as mayavada having variants like neoadvaita, kevala advaita. They are nontheistic schools and cater to speculative knowledge through inductive method.
Speculative knowledge is not reliable and cannot be concluded as authority given the limitations of human beings with limited senses or sense perception and knowledge gathering capacity through personal experience which may be limited to a particular time period or the limited existence of the jiva in human life. Hence, knowledge must be through deductive method.
The deity worship or saguna worship is with respect to the factual divine form of the Lord and His manifestations. This material body is a product of avidya and one cannot perceive spirit(soul) through material senses. The supersoul or Paramaatma is perceivable through divine eyes or eyes that have been fully cleansed of all material contamination which is possible through the knowledge of the self. This however does not reject the divine eternal form of the Lord, the sat chit ananda swarupa.
The mayavadis and their variants reject the factual form of the Lord due to their poor fund of knowledge about the nondual platform or paravyoma. Such people carry an inherent tendency to limit the unlimited divine attributes of Parabrahman which includes the manifestations of His internal potency, His divine expansions into various tattvas and His divine abodes which are not metaphorical but factual.
They limit the Parabrahman to a formless nonmoving attributeless entity which is quite akin to the perception of Islam or abrahmic religions about the allpowerful. Moreover, they disregard the distinct attributes of the Paramaatma which are almost absent in a jiva given the tattva. In this way they mislead everyone including themselves.
The spontaneous love of God is not easily awakened in the covered consciousness of the jiva and it is advised to accept certain prescribed regulations to help invoke the inherent attitude of service to Parabrahman which is misplaced in this material world in the form of philanthropy and altruism. The concocted ideas about self realisation process creates a situation where real service to Vishnu is replaced or assumed to be compensated by serving human society on the material platform. Real relief is to save the soul from repeated births and deaths and cannot be restricted to the material plane through temporary relief.
The gigantic form of the Lord that accomodates all universes extends His causeless mercy to the souls who want to connect themselves to Him through loving service and considering the limitation of the material body of humans He agrees to accept the form of matter or allows to manifest Himself in the matter transformed to His form. Hence, the deities which are made of matter(stone, wood, metal) carry manifestation of His divine energy in order to accept the offerings of His devotees to invoke the dormant love. An ignorant person sees only stone, wood and metal but not the Lord. Though He is present everywhere in His allpervading feature, His mercy to get manifested personally in the deity is the nectar of His love that is free from all blemishes.
“Nirakar” means without material form and that does not mean “no form”.
The Vedanta: Its Morphology and Ontology by Srila Bhaktisiddhanta Saraswati Thakur - Akincana Gocara