History of Mediaeval Hindu India (being a History of India from 600 to 1200 A.D.) v3.c41.s19.4

v3.c41.s19.4

(But the greatest harm caused by such bigotted notions of purity of caste was the prohibition of reconversion which came into practice even in Al-Beruni's days and without any provision in the Kalivarja texts. It seems that Al-Beruni had a talk with some learned Brahmin on the subject; for he clearly says that there is a penance prescribed for the purification of persons "carried away into a Moslem country as slaves and returning" and he actually describes the penance; but adds that the Brahmin remarked that such persons were never taken back into the caste (Sachau Vol. II p. 163). Such was the state of public opinion even in Al-Beruni's days; it is needless to state that in the course of this sub-period and later this bigotted sentiment of the Hindus must have gathered strength and persons forcibly converted had no help but to remain in the religion forced upon them. 'Once a convert always a convert' became the maxim of intolerant Hinduism and we know that thousands of Hindus have consequently, most often without their fault, become irretrievably Mahomedans and Christians.