I being an atheist was always stung by this question to which I researched and found these.
In Hinduism, which is based on the Hindu principles. The Hindu philosophy doesn’t mention that one has to believe in God as it is based on simple life. The word God hasn’t been mentioned until the eighth mandala, which states that the human of that period were unable to get an answer to the question of how they were created so to answer that they created or termed god which was first considered to be human who were thought to have evolved creating life. The in the early Vedic period was based on the cycle of nature of creation, preservation, and destruction which were named as the Brahma, Vishnu, and Mahesh. Soon after in the Later Vedic period the forces of nature were worshipped as Gods. Many Gods like were nature’s forces like Indra for lightning, Vāyu for Wind, Agni for Fire, Surya for Sun which were similar to the Egyptian belief.
People began giving human form to the After all this evil practices crept into the society as the later Vedic period began. Some people took advantage and started shaping this god according to themselves and introduced many senseless rituals to the society and became greedy which resulted in the social evils which spread in the later Vedic period. Some Brahmanas who for their own benefit divided the social structure into Varnas creating inequality among the people. These Brahmanas made this system rigid, and they began to do things for their own benefit. They began to be patronized by the ruler as they were considered to be connected to god.
This led to backlash from people as some people like the Shudras were treated with great contempt by the Brahmanas, who didn’t even let their shadows fall on them. This hatred caused a revolution which began by the advent of Jainism and Buddhism who were formed against the monopoly of Brahmanas which made life complex and resulted in evil rituals causing suffering to people. Both Buddhism and Jainism followed a simple path which attracted people and as a result there began a revolution in the society. The authority of Brāhmaṇa declined. After this revolution the social evils again crept into the Society. Before independence a period of socio-cultural revolution took place against social evils like Sati, Polygamy, and child marriage had crept into the society. The revolutionary thinkers, such as Raja Ram Mohan Roy, Dayanand Saraswati, Vivekananda went into depth an exposed the truth. They created a movement in the society which put reason and proofs which convinced people that they were misled. After attaining freedom we are still falling in the trap of ideas which were found to be misleading in the past. We need to change and understand the truth about God and tell it to people so that we all get to know the truth.
There are many ideas of what God is but many of them doesn’t suffice but a basic idea which is based on the Old Testament of the Bible and which could even be found in the Veda is that, ‘God is life’. There are many ideas about God as it still remains a mystery.