There is nothing wrong in Keeping your cast and also be HINDU, In fact that's very welcome.
My personal feeling is with all these "OBC", ST, SC- Cast Hope Loose it's Traditional Meaning.
Cast or No- cast Hinduism is INTACT, How because it's Most HUMANE, PROGRESSIVE, Scientific and above all it is Tested though Last FIVE THOUSAND YEARS, Tested against onslaught from all Theories and Religion -It absorbed them all and Digested real Good - It's Immune to all external and Internal Parasites. Will Flourish again
