ANTIOCH and EPHESUS, Turkey -- When we associate the origins of Christian faith with shepherds in the field, keeping watch over their flocks at night, it's easy to distance ourselves from history's key event. But a visit to these ancient cities makes it clear that Christianity grew up in an affluent urban society not entirely unlike our own.

 Antioch was the city where, as the Book of Acts notes, "the disciples were first called Christians." It was also the third largest city of the Roman Empire, after Rome and Alexandria, with a population that topped out probably at half a million. And it was a prosperous city whose residents enjoyed politics, wine and pornography.

 Just as American technology is improving and our ethics probably regressing, so Antioch's engineering impressed all, but its morals depressed even pagans. The first century Roman satirist Juvenal wrote that Antioch "has poured its sewage into our native Tiber -- its lingo and manners, its flutes, its outlandish harps ... and the whores who hang out round the race-course."

 The Romans could bring water from afar by impressive aqueducts and could even move rivers. A tunnel at Antioch's port city, Seleucia Pieria (now called Cevlik), shows that this last claim was no exaggeration. With the harbor silting up and winter rains leading to flooding, Emperor Vespasian (A.D. 69-79) succeeded in changing a river's path by constructing a diversion canal almost a mile long.

 And yet, early Christian leaders were not overawed by Roman power. Instead of trying to fit in, they turned aside from the marvelously pillared temples that awed visitors. Christianity's first church was probably a natural cave on the western slope of Antioch's Mt. Silpius. Peter, Paul and Luke are all said to have preached in what is now called St. Peter's Church, with its interior of fissured limestone from erosion and dripping water, and nothing else: no organ, no statues and no pew cushions (and not even any pews).

 What a contrast between the cave's simplicity and the decadence of Antioch or of Ephesus, the city where Paul stayed the longest on his missionary trips! The Roman Empire could have had the traditional DuPont Co. slogan, "Better things for better living" -- and the Christians challenged that by asserting that better things without God are idols for destruction.

 Ephesus had splendid homes and courtyards. Remnants of aqueducts show how water came from afar, to be heated for baths in big cauldrons made of copper. Ephesus even had a communal latrine where people, instead of crouching, could sit on slabs of stone with well-situated holes and water running alongside and underneath. But spiritual needs were supposed to be met by reverence offered to great leaders like the emperor, or offered to the works of human hands, big or little idols.

 Rites at the Ephesus arena were all designed to glorify Man, and the gods men created in their own image. A big day began with the slaughter of wild animals, so that audiences would understand that even beyond the boundaries of the arena, Man was in control. Arena games also included executions, designed to show that the empire is a place of order. Crucify the prisoners. Have animals tear them alive. Burn them.

 What could stand up against that affluent cruelty? What could appeal to men and women who had everything that Roman gold could buy, but yearned for something more? Luke knew: He contrasted a baby born in a manger to the Antiochians, Ephesians, and others wearing elegant robes and living in fine houses. He taught that God came to earth to redeem human beings, which means that we humans cannot save ourselves.

 The ruins of Ephesus are a warning to those of us who trust in affluence. These days, the wind roars through ancient arches by which grow thistles the size of a fist. Almost all of the flowers have massive thorns.