The fact is that the world is divided between users of the Macintosh computer and users of MS-DOS compatible computers. I am firmly of the opinion that the Macintosh is Catholic and that DOS is Protestant. Indeed, the Macintosh is counterreformist and has been influenced by the "ratio studiorum" of the Jesuits. It is cheerful, friendly, conciliatory, it tells the faithful how they must proceed step by step to reach - if not the Kingdom of Heaven - the moment in which their document is printed. It is catechistic: the essence of revelation is dealt with via simple formulae and sumptuous icons. Everyone has a right to salvation.
DOS is Protestant, or even Calvinistic. It allows free interpretation of scripture, demands difficult personal decisions, imposes a subtle hermeneutics upon the user, and takes for granted the idea that not all can reach salvation. To make the system work you need to interpret the program yourself: a long way from the baroque community of revelers, the user is closed within the loneliness of his own inner torment.
You may object that, with the passage to Windows, the DOS universe has come to resemble more closely the counterreformist tolerance of the Macintosh. It's true: Windows represents an Anglican-style schism, big ceremonies in the cathedral, but there is always the possibility of a return to DOS to change things in accordance with bizarre decisions.....
And machine code, which lies beneath both systems (or environments, if you prefer)? Ah, that is to do with the Old Testament, and is Talmudic and cabalistic.
The excerpt is from an English translation of Umberto Eco's back-page column, "La bustina di Minerva," in the Italian newsweekly Espresso (September 30, 1994).
I put this on my web site a long time ago, near when I first had a web site because I had been living in Italy and was aware of Eco. I didn't translate it myself, just copied it from somewhere else on the Net, because it appealed to me.
Personally, I'm a Quaker, which in my mind integrates some of the best things of both catholic and protestant Christianity (and relates to other religions as well).
notes added 2002-09
Further notes 2007-10
You can find a fuller version here (thanks to David Smith).
This is the page cited by Stephen Fry in the Guardian on Saturday October 27, 2007.