I never heard such a thing, and in a country with a majority Hindu population tapping one billion, thought it unusual.
So I google your exact words:
"Christians in northern India who attack and even murder Hindus who won't convert"
and every entry said the complete opposite. Hindus are attacking Christians, forcing conversions or murdering them.
Whenever Hindus are attacked by Moslems in India - and they are - they strike back and they do it twice as hard, if not more so. Even in areas with more Christians, they're numbers do not compare even to Moslems, let alone Hindus. If such a thing happened, Christians would become a thing of the past there overnight.