THERE'S an old Persian proverb that says a carpet must be perfectly imperfect, and precisely imprecise, because only God is perfect and has the right to create perfectly.

However, Ian Small's portrayal of God is more like the rug than our preconceived ideas of the almighty.

It's a bold move; one that makes him appear vulnerable. And prone to mistakes. Take the choice of Lucifer as his lieutenant, his master in might. It goes wrong almost immediately, because Old Nick declares himself as the best of all the angels and equal to the supreme being.

"The script gives God a very interesting character," says Ian. "He quite clearly does not know everything. Philip Breen, the director, who has handled this superbly, said right from the beginning 'be surprised'. So when God says 'I'm gracious and great' it's not a pronouncement, its 'hey, I'm gracious and great, how about that'? "There's a real sense of wonder."

That's the human side of God manifested as father and son. What about him as holy spirit?

"I asked Philip if he wanted me to appear in some of the other scenes just watching," says Ian. "He said no, the audience will see you there and think if he's so powerful, why the heck doesn't he step in and do something about it?"

Not to mention cutting a lonely figure for someone omnipresent.

There's humour too in Ian's Triune God.

"The script allows him contact with Lucifer, Adam and Eve and Noah. He says 'Oi Noah come here, I want you to build an ark and put these animals in it'.

"In one marvellous moment, when he has built the ark, Noah turns to God and says 'careful, the paint's not dry yet'."

Anger isn't shied away from either.

"God gives Adam and Eve a chance and he gets really furious when they let him down," says Ian. "He tells them they have mastery of the world and they're going to live in paradise.

"In a nice green touch, he says 'I'm giving you power to look after the world'. I wish the script allowed me to make more of that, really. To say if man fails in that job the world fails as well."

That said, Ian's overriding impression of God's character in The Mystery Plays is avuncular; the human characteristics allowing an audience to associate with him.

But how to steal the limelight away from Lucifer; the ultimate baddie. The guilty pleasure; the man we shouldn't be drawn to, but somehow are.

"Erm, I don't," says Ian. "I think the audience respond to him and Jesus in a much more interested way than they do to God. I hope they are attracted to him and are interested to see how he works things out.

"God does get things wrong, then puts them right through Jesus. As Jesus says, it's what his father intended."

Don't get the impression that Breen's interpretation of God is inappropriate. There is a fine line between artistic exegesis and Christian theology. All he is doing is asking us to ask again.

"At church when I say some of the prayers I think that's not quite the God I now know better," says Ian. "(Playing this role)... I find him more personal and I do think God is within us, he understands."

Like the Minster's equally old East Window towering in the near distance, the original purpose of the Mystery Plays was to instil morality; if you want to sin, be prepared for what's coming afterwards. But mend your ways and you'll be fine. Which is as valid today as it was 700 years ago.

Although the message is a bit less po-faced these days.

"There was a nice suggestion the other day that in the scene where the woman is about to be stoned for adultery and Jesus says 'let him who is without sin cast the first stone', I should appear at the back and throw it," says Ian. "The director has said I will have an answer by the end of June."

The York Minster Mystery Plays run until June 30. Box office: 01904 623568 or at yorktheatreroyal.co.uk