"Most atheists abide by the morality of the culture that they inhabit, not because they have taken the effort to reason from first principles and miraculously reached conclusions that bear a remarkable similarity to the moral system of those around them, but because lacking any moral system of their own, they parasitically latch on to the system of their societal host." (p. 63)D'Souza examines the ethical views of one atheist, bioethicist Peter Singer, to show us what ethics begin to morph into when morality is detached from God, and thus also detached from the accepted cultural norm.
We have benefited from a culture that has been immersed in the light of the Gospel message, so much so that even nonbelievers hold to many of the same moral precepts as believers do. So as our culture is pushed out of the light and into the darkness one can expect to encounter a greater and greater divide between what is morally acceptable for a Christian and what is morally acceptable for a nonbeliever. Examining the ethics of a person like Peter Singer is like looking into the dark charm our culture is about to fall into.
Some people consider Singer a provocateur who says outrageous things just to get attention. But Singer is deadly serious about his views and—as emerged in our debate—has a consistent rational basis for his controversial positions.
To understand Singer, it's helpful to contrast him with "New Atheists" like Christopher Hitchens, Daniel Dennett, and Richard Dawkins. The New Atheists say we can get rid of God but preserve morality. They insist that no one needs God in order to be good; atheists can act no less virtuously than Christians. (And indeed, some atheists do put Christians to shame.) Even while repudiating the Christian God, Dawkins has publicly called himself a "cultural Christian."
You can read Dinesh D'Souza's entire article, Staring into the Abyss, here.