In order to belong to a religion, three characteristics of the follower are required. The first and foremost is the pride in the religion. If one feels pity about belonging to a religion then it's better not to subscribe to that religion. It's important to admire the identity cherished while belonging to a particular religion. The second characteristic is the practice of the tenets of the religion. Mere pride don't work and without practice, it's a shallow identity in belonging to a religion. Last but not least characteristic is being professional in religion. One may get pride and practices too however unless the religion serves the follower with some advantage which he/she doesn't get without subscribing to that particular religion, the pride and the practices are useless. The served advantage should be real and not promising. It should be serving individualistic interests rather than socio-political ones.
Thus,
A Hindu shall take pride.
A Hindu shall practice.
A Hindu shall profess.
These three commandments apply to all religions, however, Hinduism is unique in that it has a fourth commandment which applies oppositely in Abrahamic religions.
A Hindu shall not proselytize.
The Hindu religion which is older than history had produced numerous personalities and it would be blasphemous to compare them, however, in the past five thousand years, the three whose impact on almost every facet of the religion is Vyas. In all likelihood, there were many Vyasas, a post like Shankaracharya occupied by someone of great scholarly calibre and spiritually devout life. This however indicates that the fountainhead Vyasa among the foremost Gurus (spiritual masters) was as great as Adi Shankaracharya among philosophers. He wrote a Magnus Mahabharata which encompasses all aspects of life concerning the question of Dharma (righteous action or duty). He classified the Vedas based on their recension. He wrote Brahma-Sutra which is one of the three canonical texts of Vedanta. He took the major project of writing eighteen principal Puranas where he beautifully harmonized all the Deities of then-existing traditions inspired by the Vedas. He presented lofty Vedic philosophy in lucid stories and anecdotes in the Puranas. He is the foundational pillar who gave Hindus what they practice today.
The Vedic practice was under attack from various corners, especially from the Buddhists. After the advent of Nagarjuna, the Buddhists were intellectually and philosophically very sound and committed to uprooting Vedic tradition. Then came the great philosopher of all time, Bhagavatpada Adi Shankaracharya. He established the supremacy of Vedanta over all other philosophies. He lifted a mortal man to the status of immortal God. He wrote extensive commentaries on ten major Upanishads. He wrote commentaries on other canonical texts of Vedanta viz., Bhagawad Gita and Brahman-Sutra. He travelled on foot from the southern tip of India to the Himalayas on the Northern edge of India. He established four Mathas (Spiritual Centres) in four corners of the Indian land mass. He founded Dashnami Sannyasi (monastic) order, which has produced inspiring spiritual and intellectual giants. He is the foundational pillar who gave Hindus what they profess today.
The Islamic and Christian wave swept India. Many converted due to terror or temptation. Those who saved themselves from fear and favour, could not escape criticism of idol worship and polytheism. Then came Swami Vivekanada who brought new vigour to the dying Hindu belief system. He instilled pride and honour in the belief system of their ancestors. He took idol worship and polytheism with the ultimate love and passion that other great Hindu leaders of the time shunned. He is the foundational pillar who gave Hindus what they are proud of.
