The Vedic Religion.

The Aryans did sacrifices and called forth the gods by reciting hymns (Many people still perform these rituals). Often all the hymns were devoted to the gods and were used in the sacrifices.
In Rigvedic times these gods were the symbols of the virtues of natural and godly Divine possessions and Powers. They were formless in spite of being expressed with forms at various places in the Rigveda. Although there's polytheism in Rigveda, however it's outer meaning of Vedic hymns. The inner message of the Vedas only reveals of a Supreme Power at the root. In fact the Vedic seers worshipped only one conscious power which is Creator of the Universe, i.e. root cause of the creation. Only this power is Parmatma, Ishwar, Purush or Brahm. Various gods that are referred to only reveal the various powers and qualities of the same Great Power.
Due to the divine and extraordinary nature of these specific powers, they are called as deities or smaller or inferior gods, but in reality these gods mean only the Supreme God.
"That Supreme God, although being one, is called forth and presented through several names by the seers. He happened to be the Lord of all the sacrifices which takes the form of Religion". Rigveda 6/45/16.
Through the expression of the Purush Sukta  i.e. God's hymn, the Rigveda recognized only one God as the Supreme Being and the Soul of the Universe. Rigveda 10/90.
The Supreme Power (God) is the Creator, Controller and the Destroyer of the Universe and provides power to the various gods or deities. He is Omnipresent and Omnipotent Power. Vedic Religion is called forth the Religion of Sacrifices. In general, sacrifices are known as obligations and offerings made in the sacred fire, however sacrifices do have another meaning also, such as Brahm Yagya, Dravya Yagya, Tapoyagya, Yogyagya, Swadhyaya Yagya, Dan Yagya and Gyan Yagya etc. The God has been called forth as "The form of sacrifice" and has been ordained the name of Yagyeshwar and Yagyapurush.