I really would be doing him justice. He is such an amazing writer that I'm surprised I never heard of him prior to reading that book.
I was an Englishman who lived about 100 years ago. I'm assuming he was raised Anglican. He says he became agnostic at the age of 16. He return to Anglicanism many years later and finally to the Catholic Church.
The book was writen many years before his conversion to Catholicism though you would never know it from the book. He was an Anglo-Catholic at the time. During the first half of the book he sets up the philosophic basis for the second half in which he argues for Christianity; orthodox Christianity to be exact. He describes himself as a liberal but says that what most people take to be liberal Christianity (ie. Unitarianism) is not liberal at all.
I'll just pick a few of the points.
Even non-Christians can agree that it would be just as miraculous that the Church is always wrong as it is always right. So it is logical for most non-Christians to say that Christianity has some good and some bad and is therefore a hypocracy. Chesterton, does something that perhaps all intelligent converts to Christianity must do, he embraces hypocracy as the only way to truely free man.
He cites many examples but one of his examples is violence. It's a point many critics of Christianity use to point out Christianity's hypocracy. The Church both condemned and supported violence. One of the most interesting of Chesterton's views is that he never takes a black or white view or a grey view. Balance, he believes, comes from embracing the fully white AND the fully black. Christianity preached non-violence to an extreme and also practices violence to an extreme. It allows both extremes to co-exist in its theology without combining it into a grey. This allows man to free himself from the shackles of fundamentalism (black OR white) and indifference (grey). Consistency doesn't come from trying to reconcile those to opposite views but from trying to maintain them side-by-side, consistently.
I'll quote his own words (though I don't think they're from his particular book). More profound Chesterton quotes can be found at http://www.chesterton.org/discover/quotations.html
It is not merely true that a creed unites men. Nay, a difference of creed unites men - so long as it is a clear difference. A boundary unites. Many a magnanimous Moslem and chivalrous Crusader must have been nearer to each other, because they were both dogmatists, than any two agnostics. "I say God is One," and "I say God is One but also Three," that is the beginning of a good quarrelsome, manly friendship.
Impartiality is a pompous name for indifference, which is an elegant name for ignorance.
He spends a great deal of the book explaining why he found Christinity to be appealing. He aknowledges that his book is not some proof of Christianity but his own personal journey.
Some other Chesterton quotes I found interesting...
"Fallacies do not cease to be fallacies because they become fashions."
"I believe what really happens in history is this: the old man is always wrong; and the young people are always wrong about what is wrong with him. The practical form it takes is this: that, while the old man may stand by some stupid custom, the young man always attacks it with some theory that turns out to be equally stupid."
"To have a right to do a thing is not at all the same as to be right in doing it."
"The reformer is always right about what is wrong. He is generally wrong about what is right."
"Those who appeal to the head rather than the heart, however pallid and polite, are necessarily men of violence. We speak of 'touching' a man's heart, but we can do nothing to his head but hit it."
"Once abolish the God, and the government becomes the God."
"The unconscious democracy of America is a very fine thing. It is a true and deep and instinctive assumption of the equality of citizens, which even voting and elections have not destroyed."
"It is terrible to contemplete how few politicians are hanged."
"Marriage is a duel to the death which no man of honour should decline."
"The Bible tells us to love our neighbors, and also to love our enemies; probably because they are generally the same people."
There are those who hate Christianity and call their hatred an all-embracing love for all religions."
"The Christian ideal has not been tried and found wanting; it has been found difficult and left untried."
"The riddles of God are more satisfying than the solutions of man."
"Men do not differ much about what things they will call evils; they differ enormously about what evils they will call excusable."
"Idolatry is committed, not merely by setting up false gods, but also by setting up false devils; by making men afraid of war or alcohol, or economic law, when they should be afraid of spiritual corruption and cowardice."
"All science, even the divine science, is a sublime detective story. Only it is not set to detect why a man is dead; but the darker secret of why he is alive."
"We are learning to do a great many clever things...The next great task will be to learn not to do them."
"Religious liberty might be supposed to mean that everybody is free to discuss religion. In practice it means that hardly anybody is allowed to mention it."
"Courage is almost a contradiction in terms. It means a strong desire to live taking the form of a readiness to die."
"I would rather a boy learnt in the roughest school the courage to hit a politician, or gained in the hardest school the learning to refute him - rather than that he should gain in the most enlightened school the cunning to copy him."
"It is assumed that the sceptic has no bias; whereas he has a very obvious bias in favour of scepticism."