Asked about the Prime Minister's "fiscal stimulus" package, which includes cutting VAT and increasing public borrowing, the Archbishop told Radio 4's Today programme: "I worry about that because it seems a little bit like the addict returning to the drug.
"When the Bible uses the word 'repentance', it doesn't just mean beating your breast, it means getting a new perspective, and that is perhaps what we are shrinking away from.
"What I'm worried about is anything that pushes us straight back into the kind of spiral we were in before.
"It is about what is sustainable in the long term and if this is going to drive us back into the same spin, I do not think that is going to help us."
He said people should not "spend to save the economy", but instead spend for "human reasons" such as providing for their own needs.
Dr Williams admitted it was "suicidally silly" of him to give advice on financial issues but insisted: "I want to ask where these moral questions are in the economic discourse."
Asked if the looming recession could have positive consequences, he replied: "It's a sort of reality check which is always good for us, a reminder that would some people have been calling 'fairy gold' is just that.
From an economic perspective, we want people to be buying things. That keeps money circulating through the economy, which generates more money - it isn't a zero sum game.
From a Christian perspective, we have to ask why we're buying so much useless shit, especially if we're going into debt to do so. Store up for yourselves treasures in heaven.
I'm not willing to give up all I have and go become a hermit. But one does hope we will rediscover the virtue of simplicity in these hard economic times.