Why are these people our allies?

The official Saudi Arabian tourism website lists the people who will not be issued visas:

An Israeli passport holder or a passport that has an Israeli arrival/departure stamp.

Those who don't abide by the Saudi traditions concerning appearance and behaviors. Those under the influence of alcohol will not be permitted into the Kingdom.

There are certain regulations for pilgrims and you should contact the consulate for more information.

Jewish People

Well, they really put it right out there! No Jews!

Of course, even the non-Jewish bulldozer-diver Rachel Corrie would find it difficult:

If a woman is arriving in the Kingdom alone, the sponsor or her husband must receive her at the airport.

Every woman must have confirmed accommodation for the duration of her stay in the Kingdom.

A woman is not allowed to drive a car and can therefore only travel by car if she is accompanied by her husband, a male relative, or a driver.

(hat-tip: James Taranto's Best of the Web)