Many of the 'rationalist' are confident because for long historians taught universe to be around 6000 years old. When Immanuel Kant ( he knew hindu logic) talked about vastness of time ( not hindu logic), people were aghast in Germany.
The imperialists have taken revenge, in JNU, in Dravidian politics, in Bengal cultural revolution... everywhere they got a bunch of morons to create a historical story on 2000 BCE universe for India.
All the so called SICKularists who suddenly talk of science and rationalism have been vrainwashed into this colonial fairytale in history and other subjects.
Hindus have inherent strength to question this limitation. Open up yourself. Give away the fairy tell history by ossified intellectuals. Question that assumption. If you don;t, you will slave to convert and destroy your civillization.