Hinduism is supposed to be one of the if not the strongest religions for retaining members. I'd suggest it's because it's so inclusive and so flexible that there is no reason to ever convert.
It works for rural uneducated reactionary fundamentalists (otherwise the BJP would never have beaten Congress Party, not even once).
It works for people who throw away all superstitions and put trust in science and don't even really care about questions of the supernatural.

There's something about defining God as existence itself and looking at all his incarnations as pretty much metaphoric (unless you're a fundamentalist) that makes a religion really hard to get rid of.

Of course it's also not all that great at converting people... That's why Islam and Christianity get the advantage in numbers.

But, yeah, I wouldn't hold out for the destruction of Hinduism anytime soon.
Then again I think the notion of destroying Islam is a joke as well (even if there actually was a good reason to).

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