The main reason for the survival of Hinduism for so long lies in the fact that many great Hindu personalities were born in India from time to time. They saved and/or modified Hinduism. Some of them were incarnations of Lord Vishnu. As promised by Lord Krishna in the Bhagavadgita, he incarnates on Earth from time to time to save Dharma from declining. Because of human nature, human beings deviate from the path of righteousness after a while. Therefore, god needs to interfere and bring them back on the right path. We are listing some of the famous Hindu personalities here. All of them were born as Hindus, but some later founded other religions and sects.
Lord Krishna
Lord Buddha
Lord Mahavir
Chandragupta Maurya
Chanakya
Sambhaji Maharaj
Mahatma Gandhi
Rani Laxmibai
Krishna Devrai
Samrat Ashoka
Samudra Gupta
Thorale Bajirao Peshwe
Aryabhatta
Bhaskaracharya
Kanad
Saint Dnyaneshwara
Saint Tukaram
Saint Tulsidas
Saint Kabir
Guru Nanak
Saint Ramdas
Saint Namdev
Saint Eknath
Saint Mirabai
Swami Vivekanand