Does caste exist among Indian Muslims, Christians and Sikhs?
In practice, caste-like distinctions are widely reported among Indian Muslims, Christians and Sikhs, even though the teachings of those religions proclaim the equality of believers. This is not a paradox once you see what conversion does and does not change. A person who leaves Hinduism carries his social world with him — his relatives, his marriage circle, the rank his neighbours assign him — and that social world does not dissolve at the door of the new faith.
The result is communities within these religions that function much as castes do: marrying among themselves, ranked by others, and in the case of former Untouchables often carrying the old stigma into the new fold. This bore directly on Ambedkar's own decision. He ruled out Islam and Christianity partly because he judged that conversion to them would move his people out of their own civilisation without reliably delivering the equality they promised — the caste line, he feared, would simply follow them across.