Smartas affirm the worship of five deities (commonly Vishnu, Shiva, Devi, Ganesha, and Surya), as equal forms of the one formless absolute, Brahman. The practice, called panchayatana puja, arranges the five together and allows the worshipper to hold one as a chosen focus (ishta-devata) while regarding all as manifestations of a single ultimate reality. The stance is grounded in the non-dualist (Advaita) theology associated with Shankara, for whom the many gods are provisional forms through which the one Brahman is approached.
Tradition credits Adi Shankara, the eighth-century (by traditional dating; some modern scholars place him a century or so later) systematiser of Advaita Vedanta, with formalising panchayatana puja as a way to unify diverse local devotional practice under a single philosophical framework. In the ritual arrangement, the worshipper's chosen deity (ishta-devata) is placed at the centre of a five-fold diagram, typically drawn or set with small stones or images, with the other four gods arranged around it, so that the same five-god set can serve a Vishnu devotee, a Shiva devotee, or a Devi devotee equally, each simply choosing a different centre while still, in principle, honouring all five as manifestations of one Brahman.