Unity in diversity- myth or fact

It is trying time for teachers, especially history teachers. Whenever I teach lessons on the great Indian unity, great Indian sharing and caring ( our pledge) why do I feel hypocritical?
The present generation questions. They have news at their fingertips. In school we have students giving us weekly news round up.. Cauvery issue, Dalit issue, cow vigilantism, gender inequality issue, honour killing issue...

And my voice drones on ...The Preamble of the Constitution says....