DHAHRAN, Saudi Arabia — Somewhere in Jidda, in a dark, crowded prison cell, six young men await their encounter with Islamic justice for ambushing a bus with guns this month and slightly wounding two American GIs.

Justice for the men--four Palestinians and two Yemenis--is apt to be swift. They will be tried as terrorists under the same verse of the Koran that was used to deal with highway robbers in medieval times, and if convicted, their punishment appears clear: The ringleader will be beheaded in a public execution, and his followers will each suffer the amputation of two limbs--a hand and a foot on alternate sides of the body.

To many Westerners, Islamic law, or \o7 sharia, \f7 is one of the most perplexing aspects of a religion that is followed by a quarter of the world's peoples. The beheadings may seem barbaric to societies that prefer the bloodless neatness of lethal injections, the gallows or the electric chair; the stoning to death of adulteresses may seem better suited to nightmarish visions of ancient times than to life in the 20th Century.

But Saudi Arabia, the only Arab country whose legal system bears no traces of France's Napoleonic Code, provides startling proof that the \o7 sharia\f7 should not be dismissed out of hand, for this desert kingdom is probably the safest, most crime-free country on Earth. Muggings, robberies, murders and burglaries are not even vague threats to daily life here.

At the Dharhan International Hotel, where most of more than 900 foreign journalists covering Operation Desert Storm are staying, millions of dollars worth of communications gear, satellite transmitters and generators are stacked on the pool deck, unattended. Hotel room doors are often left open, computers, cameras and traveler's checks in plain sight.

When a journalist Wednesday gave a local businessman the equivalent of $2,900 to cover a month's rental of his car, a bellman appeared at the reporter's door an hour later, bearing an envelope stuffed with riyals. The journalist had overpaid.

\o7 Sharia \f7 may be translated literally from the Arabic as "the road to a watering hole," and from that derives the meaning of "the path of God." It differs fundamentally from Western law in that it is not, in theory, man-made. It is divine, laid down by God, a code of social and religious duty that deals not just with law and punishment but with every aspect of life--from how Muslims pray in the mosque to how they conduct their affairs in the marketplace.