This is one of the funniest and cleverest novels I have ever read. It is also one of the deepest. Behind the clever adaptation of the Don Quixote story to a context in post-Franco Spain there is a dance of ideas, much as Shaw's plays are a dance of ideas, and the questions dealt with are the biggest and most fundamental that we all have to deal with.
An innocent and un-intellectual Catholic priest sets out on a holiday with a communist politician, and their discussions, always friendly and courteous and greatly assisted by wine, centre on their respective faiths. The communist faith is much the more straightforward - the ex-mayor, defeated at a recent election, finds the general outlook of Marx congenial, he finds that doubt shackles freedom of action, and that's about as far as his introspection goes. Catholicism is about bigger issues altogether, such as do we go to heaven or to hell for all eternity, and the concepts involved, for someone who really thinks about them honestly, are sufficient to unseat anyone's mind. There is no real alternative to thinking about them, so in the interests of peace of mind what people do is to think about them not honestly but either ingenuously or disingenuously. Graham Greene, like Muriel Spark, was a convert to Catholicism, and like Dame Muriel his treatment of it in his writing is wry and ironic. What he really 'believed' is not quite clear and I'm sure not meant to be. Indeed he even casts some doubt around the question of what 'belief' actually consists of, and rightly so in my own view. At one point Father Quixote admits that a certain doctrine is one that he believes out of obedience, an admirable attitude for traditionalist believers whether Catholic or communist - you believe x because you're supposed to believe it and you'll be in trouble if you don't. Greene quite obviously sees that Catholic doctrine evolved as a book of rules to keep people under control. What started as religious and ethical teaching developed rapidly into thought-enforcement and thought-policing, but the matter goes even deeper - behind it all there is supposed to be a God whose word the ecclesiastical power-structure dispenses, and this God is not, like Marx, someone who certainly exists but only a hypothesis. How much further Greene wishes us to pursue this line of thought I'm not clear, but for me two considerations follow - firstly what is supposed to be God's word is actually a human construct foisted on the hypothetical God, something that to me seems outright blasphemy; and in the second place we have a clearer idea these days what the Creator has created, and such a Creator is not likely to bear much resemblance to Jehovah in the scriptures having to assert his authority against Baal, Dagon etc at intervals. Indeed if there is one crumb of comfort in the contemplation of such a Creator it's likely to be that he will take little or no notice of our insolence in presuming to speak for his intentions.
Towards the end of the book Greene says something to the effect that in the absence of certain knowledge one goes for the next best thing. For him this is 'faith', for me it's probability, as best I can assess that. Greene is able, as I am not, to find a sense of 'believing' that takes in the soul as well as the mind. When I say that I believe something I mean that it seems to me true or probable, and considerations that bring me spiritual comfort are unrelated to belief in this sense entirely. Greene seems not to go so far, but I venture to think that he's nearer to my way of seeing things than to 'faith' in the conventional sense. What is completely unmistakable is the irony with which he observes the way that the devout have of finding support in the scriptures and in philosophy built on them for convenient viewpoints and courses of action.
The book is not so much about the rival ideas, nor even so much about what people do with these as about what the ideas do with people who for some reason adhere to them, as if the ideas had taken on a higher life of their own, dominating and controlling the very people who create them and without whom they could never exist. This may indeed be what we call divine in them. What is divine in a more earthly sense about this book is the humour and ingenuity of it all. It is a simple story as well as a battle of ideas, and a touching one too, with emotion and human affection finally dominant over the intellectual side. A delightful book, a beautiful book and I would even say a great book.