Why Is India Called ‘Hindustan’ ... If It Is A Secular Country?

Let me tell you a secret: Hindustan is derived from Indus, not Hindus.

From Wikipedia: 
Secular: Not Connected with religious or spiritual matters 

Hindustan (Hindi: हिन्दुस्तान) both Hindustan, Hindoostand or Indostan, literally "land of the Indus", is a popular name for the Indian subcontinent

Hindustan is derived from the Modern Persian word Hindu. In Old Persian, the region beyond the Indus River was referred to as Hindus (which in turn is derived from Sindhu, the Sanskrit name for the river), hence Modern Persian Hind and (as a borrowing) Hindu. This combined with the Iranian suffix -Stan (cognate to Sanskrit Sthana, both meaning "place" results in Hindustan, as the land on the other side (from Persia) of the Indus.

"Hindustan" is made up of 2 words, "Hind" and "Stan".

Hind in Arabic language translates to "Ind" in Latin, as in Indus River. Thus pointing to the land where river Indus Flows. Hence Hindustan is nothing to do with any religion. It's exactly the same as India in Latin, which again means Land of Indus River. And people living in "Hindustan" are called Hindus in the Middle Eastern tongues, relating to Indian in Latin borne languages. Again it has nothing to do with any religion. And it is for a fact that all Indians are Hindus, irrespective of what religion they practice. Hinduism is not a religion per say, it is "the way of life, of people/civilization which began and flourished along River Indus". 

Please do not make a mess of "Hindustan" with stupid questions born out of ignorance.

Get your facts right!