In 1941, the Muslims were in absolute majority in Punjab accounting for 53.2 per cent of the total population. The Hindus made 29.1 per cent of the total, the Sikhs 14.9 per cent, Christians 1.9 per cent, and others 1.3 per cent. Such a distribution was significantly different from that obtaining in 1881 when the Hindus made 43.8 per cent of the total population, the Sikhs 8.2 per cent, and Christians 0.1 per cent. The Muslims, at 47.6 per cent, were well short of an absolute majority.

Evidently, that there was a distinct fall in the percentage share of the Hindus while the Muslims and the Sikhs made a significant headway in their proportion. The Christians also recorded a noticeable increase in their numbers. A big erosion in the percentage share of the Hindus was caused by the conversion of many of them to Islam, Sikhism and Christianity. Such a change of religion was much more typical of lower castes among the Hindus, such as chuhras, chamars, jhiwars and malis. Conversion was negligible from the higher castes, such as Brahmins, Aroras, Khatris and Aggarwals (Census of India, 1931, Punjab, p. 328).

Link: http://www.global.ucsb.edu/punjab/sites/secure.lsit.ucsb.edu.gisp.d7_sp/files/sitefiles/journals/volume11/no1/6_krishan.pdf