The Aryan people worshiped several gods and goddesses. In the religious scriptures, Rudra is termed as the great God and he is also called Shiva who is worshiped even up to this age by the common people.
The religious spirit behind the worship and devotion of the people has undergone a revolutionary change in the Later Vedic Period. The Brahmin class coined new and elaborate ceremonies and sacrifices where as many as 17 priests would be required and the ceremonies would take several years to be completed.
There were many elaborate instructions as how to perform a good sacrificial ceremony to please god and there were indications that any shortcoming in the sacrifice would displease the gods and would entail their wrath upon the sacrifice. Thus, the Brahmins made their position very strong in the society.
Since, the Brahmins got themselves detached from the worldly cares, as their source of income was practically guaranteed from the Vaishya class and the royal patron, they actually devoted themselves to the service of the literature and logic and philosophy.
The Upanishads are full of high metaphysical philosophy wherein discussion of Sankhya, Yoga, Nyaya, etc. has been made in great details. The philosophers believed in Atman or Brahmin, the Creator and the Supporter of the world who was omnipotent and omnipresent. It is for the first time that we hear of transmigration of soul and the circle of birth and rebirth. This naturally led to greater emphasis on a pure life as it was upon the Karma of man that his future life would depend. The good or bad acts of a man would affect his future birth and this proved instigation for the people to lead a very pious life so that a better future birth may be guaranteed. By better rebirth they could hope, in the end, to have mukti or nirvana.