Dawkins and Hitchens contend that God is not demonstrable according to the scientific method. ... What about "equality" and "justice" and "rights": none of these things have any material existence, so does that make them illusions?
Equality, justice and rights are concepts invented by humans. If you think the "right not to have soldiers quartered in your home" existed in any meaningful sense before a document creating it was composed and ratified and enforced, then you've been drinking the Rego* Kool-Aid. If you think some sort of physical Force would prevent soldiers from being quartered in your home, then you're delusional. This right is 'just' an agreement, an idea, a contract.
*Just an in-joke, not a famous political philosopher
So if Dinesh believes in a god that exists in the same way that 'justice' does, I'm fine with that - a manmade concept that has effects on the world through the people who lend credence to it.
(as for consciousness and free will, which DD also brings up, certainly consciousness (whatever it is) is demonstrable in the same way that, say, anger or awareness are. Free will is more of a philosophical problem, and the philosophers have not yet come to any agreement on whether it 'exists' or not. I tend to side with the philosophers who do indeed believe that free will is an 'illusion'.)