There is one bit of advice given to us by the ancient heathen Greeks, and by the Jews in the Old Testament, and by the great Christian teachers of the Middle Ages, which the modern economic system has completely disobeyed. All these people told us not to lend money at interest: and lending money at interest - what we call investment - is the basis of our whole system.
This is certainly challenging. But there are some subtleties that should be kept in mind. First, the Old Testament passages seem to be mostly concerned about charging interest to the poor and needy and/or Israelites. Second, the church banning the charging of interest has a long and troubled history which is nicely recounted on the Wikipedia entry on Usury. For example,
Lateran III decreed that persons who accepted interest on loans could receive neither the sacraments nor Christian burial. Pope Clement V made the belief in the right to usury a heresy in 1311, and abolished all secular legislation which allowed it. Pope Sixtus V condemned the practice of charging interest as "detestable to God and man, damned by the sacred canons and contrary to Christian charity."
On the other hand, I agree with Lewis [and the Global Financial Crisis provides significant empirical evidence!] that we have a problem. God wants us to forsake greed and be concerned with justice and equity.