When Vaishnavism speaks of antaryami avatara, it is believed that the Supreme Being as residing in the inner recess of the heart assumes a subtle divine bodily form (vigraha-visista) so as to enable the upashakti to meditate on God. In Yoga system, meditation is twofold- salambana and niralambana. The former type which is the first stage of samadhi needs an object that could be visualised, whereas the latter which is the next higher stage can be done on a formless entity (svarupa). Before proceeding to the higher stage of upasana, it is necessary to meditate on a divine vigraha. It is believed that for such yogis as wish to do the meditation on the divine Being which is present within one's own heart, God, out of love and compassion, takes on a bodily form (vigraha). This is the purpose and justification for manifestation of God as antaryami.
This theory is admitted on the strength of the scriptural and Smriti texts. The Taittiriya Upanishad refers to the heart as the abode of the Supreme Lord and says that at the centre of it, Paramatman resides in a subtle form. It also gives a physical description of Paramatman as having the complexion of dark blue (nila-megha) lustre similar to the lightning. In a later passage of the same Upanishad, it is stated that the Paramatman resides in the heart which is of the size of a person's thumb. The implication of all these statements is that Paramatman dwelling in the heart of the upasaka has assumed a spiritual subtle bodily form to enable the yogi to perform the meditation on Him. One of the thirty - two vidyas or upasanas laid down in the Vedanta includes dahara-vidya, which according to Ramanuja is nothing other than the upasana on the Paramatman within one's heart. If it were pure formless or undifferentiated svarupa of Brahman, which is vibhu (omnipresent), it will not serve the purpose of meditation. To meet this purpose, God assumes a bodily form. This is the significance of antaryami avatara, which is distinct from all the other kinds of manifestations. This fact has been well brought out by the Satvata Samhita which states: 'For those individuals who have already reached a stage in the upasana by following the eightfold yoga discipline, and who wish to do further upasana on the Paramatman residing inside the heart, this Paramatman as antaryami becomes the object of meditation.'