If God knows the future, then He knows how I will behave in advance, and so I have no real choice in the matter. My fate is predetermined. Some of us are predestined for heaven. Some of us are predestined for hell. This is John Calvin's idea of "double predestination". Human agency is a fiction.

Few ideas can be so apparently inimical to the spirit of our age. We don't buy this idea of God, we don't buy the metaphysics behind it, and we certainly don't buy this understanding of human agency. One of the best things about doing without God is that human beings can now experience themselves as free. Except – and here is the thing – we are, in fact, buying this idea, and by the million. Within 24 hours of Grand Theft Auto V being released in September last year it had sold more than 11m copies. My son has been nagging me to get it for him. But he is way too young.

Set in some dystopian version of Los Angeles, the game is an "open world" environment, giving the player the impression of complete agency. Within the game, you can roam free, apparently doing what you want and when you want. Agency is the key word here, and central to the argument of Janet Murray's hugely influential book Hamlet on the Holodeck: The Future of Narrative in Cyberspace published back in 1997.

Stories shape how we think and act. And the sorts of stories we tell ourselves are themselves shaped by the technical possibilities available. Just as Johannes Gutenberg and his printing press ushered in one sort of literary revolution, so too computer technology ushers in another. With computer games, one can actually step into the story and determine its course, immerse oneself in the narrative to the exclusion of all else. It feels more like life itself. The possibilities seem endless. The text doesn't control you, you control it. "You can do whatever you want in it, Dad," was my son's unsuccessful pitch.

Oh how Calvin would chuckle. He would love the illustrative potential of GTA. "Wake up!" I imagine him shouting. You are not creating this world. It has been created for you by unseen designers working in Dundee. And it doesn't give you real agency. Yes, to some extent you can do what you like, but you cannot be who you like. You are cast as a gangster. You can hijack cars, shoot the police and pick up strippers in bars. But you will always be a gangster. That is predetermined. It only gives you the illusion of agency. And this illusion of agency is precisely what the world's real unseen designers (currently in Davos not Dundee) want you to have because it robs you of any real control.

What a metaphor for modern life, and specifically for the illusions of free-market capitalism. Just to be clear: I don't buy predestination or any of the metaphysics behind Calvin's theology. I don't buy the idea that God is some super-intelligent grand designer secretly pulling the strings. Richard Dawkins is right about all that.

But what an irony that just as we think we are clear of this idea, so many of us immerse ourselves into a world in which these conditions really do operate. For unlike chess or Scrabble, where the rules of the game are transparent, the rules of GTA are hidden in the code, thus generating the illusion of agency. This is also how capitalism makes us feel free. You can do whatever you like, as long as you understand that your freedom is freedom to shop and to buy and to grow the economy.

For the little boy that is nagging me for this new game on Oxford Street is being manipulated by advertising and peer pressure. And one day he will have his way and get this game. I know it. Depressingly, it feels inevitable.

Twitter: @giles_fraser