Brahman, Satchidananda, may be thought of as an infinite ocean of Existence, Consciousness and bliss. All the devatas are aspects of this infinite ocean.
The three main .. deities - the Trinity consisting of Brahma, Visnu
and Siva - along with their consorts, form the first aspect. Here all
the .. deities are considered to be different facets of God, the
Uma Haimavati appears in the Kena upanishad. She points out to Indra that the yaksha they have seen is brahman and the deva-s won their victory due to brahman.
अथेन्द्रमब्रुवन्मघवन्नेतद्विजानीहि किमेतद्यक्षमिति तथेति
तदभ्यद्रवत्तस्मात्तिरोदधे ॥ 3.11॥
स तस्मिन्नेवाकाशे स्त्रियमाजगाम बहुशोभमानामुमाँ
हैमवतीं ताँहोवाच किमेतद्यक्षमिति ॥ 3.12 ॥
सा ब्रह्मेति होवा...
Swami Sivananda in "All About Hinduism" Page 115-119 writes
Idol or Murthy (Vigraha), Sun, Fire, Water, Ganga, Saligram, Linga are
all symbols or Prateekas of God which help the aspirants to attain
one-pointedness of mind and purity of heart. A symbol is absolutely
indispensable for fixing the mind. For a Bhakta or a sage, there is
no such thing ...