Do u know something called Culture ... if no then there is a thing called Hindu Culture ... which all Indians follow irrespective of religion ...
it includes Respecting Elders , Religious Tolerance , Freedom of thought , eating from Right hand only , Visiting each others place of worship, Respecting Motherland & considering Mother India equal to ones god etc etc... which is unique only to Hindu culture which all of India follows ... who dont follow these we consider them aliens to our society including any Indians who doesnt ...
& no Even Indian Muslims have culture entirely different from other Muslims ... if u try to speak Urdu in front of a Muslim from Kerala he will open his mouth & watch u like a alien ... the Muslims from kerala have culture more resemblance to Hindus of Kerala... song dance etc like Oppana , Mappila Paattukal , Kolkali , Duff Muttu etc ... which r indigenous to Muslims of Kerala only ...
so yes they very well come under the cultural shade of Hinduism ... so they r Hindus as well culturally ...