In a year when the Standard & Poor's 500 index has nudged up barely 5 per cent, investors would have done better by investing according to the principles of the Koran.

Among the small but rapidly growing band of faith-based mutual funds, the main US Muslim fund has beaten funds run according to the principles of the Catholics, the Mennonites, the Presbyterians, and the evangelical Christians. In fact, with the $100m Islamic Amana Growth fund posting a 22 per cent return for the year, they have pretty much beaten everyone, according to data provided by Lipper.