If God is formless, did Shiva, Vishnu, Brahma forms of the Lord really exist or were they imaginary?
God, who is beyond name, form, attributes, time and causation takes a form and a name with divine attributes for the redemption of mankind. This, He does in His infinite compassion, because the beings who dwell in the mind-body-attribute complex can easily relate to God with form. After many years of spiritual practices and with the purification of the mind, one moves from the form to the formless. At that stage, the seeker realizes that God is both with form and without form. He is both immanent in the creation and at the same time, He is transcendental. Examples given of God without form is like the vast ocean, and God with form is like the icebergs, which can again merge back into the ocean. God without form, which is comparable to Satchidananda (being-consciousness-bliss), takes a beautiful divine form with a sweet name, comparable to the iceberg, because of the intense love, prayers and devotion of the devotee. Thus the form becomes formless, and the formless assumes a form from time to time, depending on the needs of the time and the intense longing of the devotees.
Yes, Shiva, Vishnu, Brahma exist – as God can appear in any name or form as per the longing of the devotee – as He is all names and forms, and at the same time beyond all names and forms.