1) Raja Rammohan Roy:

He studied several religious philosophies like Hinduism, Islam, Christianity and Sufism. Having studied various religious books he was convinced that there is only one God and that worshipping of idols and making sacrifices were incorrect. He was convinced that all great religions had the same common beliefs and it was incorrect to criticise the religions of others. He also believed that we should accept a religious belief only if it is rational and if it is beneficial to people. He rejected the authority of priests and called upon people to study the original books of their religions. He published his ideas in magazines and books using the new technology of printing to reach out to maximum number of people.

2) Swami Vivekananda: 

He believed that Hindu religion was superior to all others. He emphasized the teachings of Upanishadas which were being translated and printed in large numbers.

3) Swami Dayananda Saraswathi:

He studied the Vedas and was convinced that they contained the true religion and he rejected all later additions to Hindu religion like many gods and goddesses, idol and temple worship and Brahmanic priesthood and caste system. He advocated worshipping one Supreme God through simple rituals and recitation of Vedic mantras. He rejected all other religions as false religions and wanted Hindus who had converted to other religions to return to Hinduism based on the Vedas.