Shuddi Movement

This movement was started by Arya Samj in earlier part of 20th century to the main aim of the movement is to bring back the Hindus to their religion own religion, who have been change to other castes. The word "Shudhi" is a Sanskrit word and it means cleansing, purifying and freedom from defilement and purification.

Source : Wikipedia

There was vast difference in the scriptural authorities of these religions as Islam and Christianity claimed divine authority for their Koran and Bible respectively.

while Vedas of Hinduism didn't put up such claims. Founder of Arya Samaj. Dayananda then strived to give the, Vedas the similar degree of supernatural authority. Arya Samaj launched shuddhi movement to bring non-Hindus back to Hinduism this process was called shuddhi. The concept of Shudhi played a major roll and a few Arya Samaj leaders recognized the unifying potential of shudhi. The slogan was "India for Indians". Swami Dayanand Saraswati said that the Destiny of India lay in the revival of the Vedic religion, and gave the slogan "Back to the Vedas".

This process of reconverting Hindus from Islam and Christianity was accompanied by a Sanghathan movement.