"When a man stops believing in God he doesn't then believe in nothing, he believes anything."The recognition here is that Man is by nature a religious being. We have no choice in the matter; we must believe in something, venerate and serve something or someone. Man's religious nature must express itself in some manner; if not toward God, then in some other way, perhaps even in a self-constructed system of beliefs and values.
Intimately connected with our religious nature is our moral sensibility. Man must have moral values; he must recognize and love that which is good, and recognize and hate that which is evil. A man may be immoral; only dumb animals can be amoral. Similar to the Chestertonian observation, if I spurn sound moral values I won't be completely void of moral values, but will have disordered, possibly nonsensical ones.
This may explain many curious current trends. According to sound moral principles, elective abortion is an unmitigated travesty. Most other moral issues pale in comparison to the wholesale slaughter of millions of completely innocent and wholly vulnerable human beings. No mother is helped by the murder of her child, and abortion is never a valid 'solution', far from it. The vile trafficking in human embryonic body parts, and the ghoulish practice of human embryonic stem cell research are further examples of moral values run amuck. Yet our culture pressures us to ignore or, at least, to minimize the travesty of abortion. We must likewise minimize or ignore the practice of sodomy, and pretend that homosexual liaisons are legitimate, and equivalent to marriage. That is to say, our culture demands that we relinquish or downplay sound moral principles.
This is precisely where the nonsense starts. Having spurned a sense of outrage over such basic moral evils, many folks must then scratch to fill that void, and find themselves being outraged over lesser moral evils like second-hand tobacco smoke or cruelty to crabs . Some will weave moral indignation from non-moral events like a bridge collapse or a devastating hurricane. Nary a day goes by without news of some group expressing outrage over some non-moral or comparatively petty matter.
The operative term in all this is sound moral principles, according to which the deliberate taking of an innocent human's life is categorically abhorrent. A corollary to the opening quote might run as follows:
"When a man stops being outraged by abortion, he will be outraged by almost anything."
Note 1: Whole Foods Market, while avoiding all real or imagined cruelty to crabs, is a corporate sponsor of Planned Parenthood.