Chesterton on patriotism

In his classic book Orthodoxy, G. K. Chesterton famously said that the doctrine of original sin is the part of Christian theology that can really be proved.  What he had in mind, I think, is the part of that doctrine that holds that as a result of the Fall, our capacity to obey even the most obvious precepts of natural law has been gravely impaired.  I think this impairment is indeed obviously real.  One illustration would be the way people find it so difficult, in one area of human life after another, to adhere to the virtuous middle ground between opposite extreme vices.  When we aren’t gluttonous, we tend to become overly fixated on dieting and healthful eating.  When we aren’t drunkards, we often become prigs who scold even those who drink in moderation.  And so on.  Worse, those in thrall to one vice often suppose that the only alternative is the opposite extreme vice.  Sober moderation eludes us.