In ancient times, when organized religions didn't exist, the worship of Fire was common on all parts of the Earth. The Fire rituals where conducted, Awareness or sense of I AM was worshiped as God in the human being, and the Sun was understood as direct emanation of God.
In Vedic tradition Fire is called Agni. It is considered as first and the foremost One, the One trough whom all creation came into being.
Agni is the force that from seeming nothingness makes universe into existence. Everything comes forth with the help of Agni. All consciousnesses and devas cannot do anything without its work and that's the reason why all devas worship Agni.
Agni takes our devotion, our prayers and our mantras to the Absolute God. All gods are as well worshiped trough Agni in Homa, Vedic Fire ritual.
Fire is intelligent Force that is omnipresent as invisible Fire in matter, as the Fire we all know (Solar) and as the Spiritual Fire. It has all the wisdom of the creation as all creation comes trough It. By connecting with Fire we can gain that wisdom and also purify ourselves. We should meditate in front of the candle or Fire and surrender our worries, problems, negative emotions and karma.
Every time we use the Fire we should consciously connect with It.
Fire is our own Awareness and our own sense of I AM.
AGNE NÂYA SUPATHÂ RÂYE ASMÂN
VISHWÂNI DEVA VAYUNÂNI VIDWÂN.
YUYODHYA ASMAD JUHURÂNAM ENO
BHÛYISHTHÂM TE NAMA UKTIM VÎDHEMA.
“Oh, Lord Agni, the foremost one,
the knower of the intricate Paths of creation!
Lead us by the simple righteous Path
to felicity. Destroy our past Karma,
eliminate from us the attraction
to dubious and ignorant paths.
We offer our worship to you in obedience.”
- ''Upanishad Isavasya''