No child is too young to become a cosmopolitan multiculturalist. And now that Islam is a hot topic in America, not to mention probably the fastest-growing religion in the world, two new books offer the discerning young reader a glimpse of the Islamic world. Well, O.K., these books are probably aimed more at the discerning parents of the undiscerning kid, who will doze as Mom or Dad reads aloud about the mihrab, the minber, the muezzin and other features of Islam. But they make a lovely introduction -- and I mean lovely, for both books are gorgeously illustrated. David Macaulay...