The religion of a man can be defined as the set of values and norms followed by a person in his daily life. Religion has evolved from the worship of nature to that of the worship of personified gods and observance of complex rituals.

The Sanatan Dharma which has now evolved into a complex religion with varied rituals and worship of gods in anthropomorphic forms; which is now a basket of varied forms of worship by various sects of this branched out religion, had also evolved from the worship of nature. The Sanatan Dharma of today varies greatly from the earliest form of this religion. The source for the earliest form of this religion is the Rig Veda which is the oldest of the Vedas so sacred to the Hindus. The hymns of the Rig Veda dedicated to the various Gods worshipped by the earliest Aryans who settled in India clearly indicates the vast difference between the Aryan religion of the past and present.
 
The earliest human beings were totally dependent on the power of nature. The Rig Vedic Aryans who settled on the Indus plains and then gradually began to move towards Ganga – Jamuna plains, too were dependent on Nature. May be it was therefore the Rig Vedic religion mainly centred around the worship of Gods who were largely personifications of the power of nature. The Gods although conceived as human (having anthropomorphic forms), their body parts were only figurative illustrations of the phenomenon of nature represented by them. The Rig Vedic religion mainly stresses upon the power of nature. It was above costly rituals and laid stress on simple rituals and moral values.

The Gods stated in the Rig Veda are 33 in number, being divided in 3 groups of 11 distributed in earth, air and heaven but the actual number of deities are much more. The celestial gods are Dyaus, Varuna, Mitra, Surya, Savitr, Pusan, the Ashvins and the goddesses Usha and Ratria. The atmospheric gods are Indra, Apam-napat, Rudra, Maruts, Vayu, Parjanya and Apas. The terrestrial gods include Prithvi, Agni and Soma. The rivers such as Sindhu (Indus), Vipasa (Beas), Sutudri (Sutlej) and Saraswati are often lauded as terrestrial goddesses.

Gods as personifications of nature were not the only kinds invoked in the Rig-Vedic hymns. With the advancement in thought there grew a class of abstract deities. Such ideas developed with the growth of questions such as those which sought to define the very existence of nature itself. Thus grew a class of deities such as Dhatr (creator), Prajapati (lord of creatures), Vidhatra (disposer), Dhatra (supporter), Tratra (protector), Netra (the leader). The second and smaller class of abstract deities are personifications of abstract nouns. Thus occurs names such as Manyu (wrath), Sraddha (faith), Anumati (favour of the gods), Aramati (devotion), Sunarta (bounty), Asuniti (spirit-life), Nirrti (decease), Aditi (liberation).
 
Goddesses play an insignificant part in the Rig Veda. The most important goddess is Usha being mentiond 300 times in the Rig Veda and has 20 hymns addressed to her. Next to her in importance is Saraswati.  Other goddesses include Prithvi (earth), Ratri (night), Aranyani (goddess of the forest). The consorts of the great gods lack individuality, e.g. Agnayani, Indrani and Varunani (consorts of Agni, Indra and Varun).

Another peculiar feature of the Rig-Vedic religion is the invocation of the gods as pairs, e.g. Mitra-Varuna. There are also groups of deities mentioned frequently such as the Maruts, Adityas, Vasus and Visvedevas.
 
Lesser divinities include the Rhbus, a deft-handed trio, who by their marvellous skill acquired the rank of deities. Occasional mention is made of Apsaras (water-nymphs). However the name of Urvashi only is mentioned among all the Apsaras known to us. A few other divinities of the tutelary order include Vastoshpati (Lord of the Dwelling), Ksetrasya-pati (Lord of the Field), Sita ‘the Furrow’ invoked to dispense crops and rich blessings.

The demons are often mentioned in the Rig veda. The Gods although called as Devas, were also mentioned as asuras, although later they came to be identified with negative forces.
 
Sacrifices often formed an important part of the rig vedic culture. Temples, alters and hereditary priestly class were conspicuously absent. Sacrifices were simple involving only the householder as the officiating priest and necessitating oblations of milk, ghee, grain, flesh, etc. However there was a complex form of sacrifice involving many priests and mainly undertaken by the wealthy or the monarchs.

The religion of the Rig Veda was rolled in the lap of nature. It was associated with real life and was above abstract complexities, although it should be added that some of those customs still are practiced without even our knowing it. Changing times have put a veil on the lost religion of the Rig Veda and we have now lost track of the pristine religion of the Aryans. Maybe this is an indication that we have lost a part of our culture. 

References:

• Macdonnel, A.A., H. Oldenberg, F. Max Muller(Tanslated)(2011); The Golden Book of The Holy Vedas; Vijay Goel; Delhi
• Singh, Upinder(2012); A History of Ancient and Early Medieval India; Pearson; Delhi
• Saha, B.P., K.S. Behera(1994); Ancient History of India; Vikas Publishing House Pvt. Ltd; New Delhi
• Tripathi, Ramshankar(1999); History of Ancient India; Motilal Banarsidas; Delhi
• Ray Chaudhuri,S.C.(1998); Socio-Cultural and Economic History of India; Surjeet Publications; Delhi
• Lunia, B.P.(2001); Evolution of Indian Culture; Lakshmi Narain Agarwal; Agra