Ask her this: how can she account for good and evil?
According to atheism, “nature is all there is, all there was, and all there ever will be”, as Carl Sagan put it. Is morality a physical thing? An ore you can mine from the ground, or a serum you can inject into your body? If not, then it does not exist; if there’s no God, then morality is just another superstition of a bygone era.
Think I’m being unfair here? This is precisely what Friedrich Nietzsche and Arthur Schopenhauer believed, and they are among the great-granddaddies of modern atheism. I also like to point out another atheist who exposes Richard Dawkins and Sam Harris for the sissies they are: H.P. Lovecraft.
Lovecraft was an author of short stories like “The Call of Cthulhu”, “The Dunwich Horror”, and “at the Mountains of Madness”. His genre, called “cosmic horror”, is meant to illustrate the fact that humanity is not important. Lovecraft knew that, if there is no God, then the human race is the compost of the cosmos that was lucky enough to self-replicate, and nothing more. He famously quipped that “life and death, good and evil… are nothing.”
Needless to say, the “Cthulhu Mythos” tends to attract a lot of nihilists.