‘A.D.’ AND THE FLOWERING OF JUDEO-CHRISTIAN CIVILIZATION : ‘A.D.’is as much a treatise on politics, power-brokering and corruption as on : Christianity. : RELIGION AND POLITICS SHARE BILLING

If big and beautiful automatically meant better , then “A.D.” would be the best of the best.

The 12-hour NBC miniseries (8 p.m. Sunday, 9 p.m. Monday through Wednesday and 8 p.m. Thursday on Channels 4, 36 and 39) is a grandly staged enormity, a simply gorgeous spectacle--filmed in Tunisia and richly colored in sepia and gold--about clashing Romans, Christians and Jews in the years immediately after the death of Christ.

Everything about “A.D.” says . . . important , that what we are watching unfold, on magnificent sets astutely copied from the Roman Forum, old Jerusalem and other historic sites, is no less than Western Civilization itself.

“A.D.” is that big.

So big that schools have been sent educational guides for use as teaching tools. So big that NBC has taken the unusual promotional step of sending TV critics a specially bound and indexed loose-leaf notebook crammed with photographs and printed material touting “A.D.”

“A.D.” is that big and--often--that boring.

Much of the time it’s a slow-moving behemoth that sprawls across five evenings, a gleaming giant tortoise that is more a tribute to size and splendor than to great storytelling.

Producer/co-writer Vincenzo Labella was responsible for two other NBC blockbusters, the splendid “Jesus of Nazareth” and the overrated Emmy winner “Marco Polo.” His good intentions are evident in “A.D.,” along with those of director Stuart Cooper and co-writer Anthony Burgess (“Jesus of Nazareth,” “A Clockwork Orange”).

Their story covers the tumultuous reigns of four Roman emperors, beginning with Tiberius and the Resurrection of Christ and ending with the demise of Rome and Nero. Meanwhile, a new religion emerges from conflicts between traditionalist Jews and Jewish Nazarenes (Christians), one that manages to survive Roman oppression.

“A.D.” is as much a treatise on politics, power-brokering and corruption as on Christianity, and is especially fascinating in recording the backstabbing and murderous plots of the ruling Romans.

History recalls the early emperors and their collaborators, with the possible exception of Claudius, as largely amoral and wicked. Some were apparently even deranged, as in the case of the monstrous and murderous Caligula, who arbitrarily terrorized practically everyone in reach. It is fun watching them solidify their power and attempt to rule the empire.

The late James Mason makes his last performance a good one, cutting a cowardly and debauched figure as the aging Tiberius, whose sexual tastes while in self-imposed exile on Capri were said to have included children. And Ian McShane (Judas in “Jesus of Nazareth”) is fittingly corrupt as Sejanus, the ambitious Praetorian Guard leader whom Tiberius allowed to become almost the de facto ruler of Rome.

Tiberius is succeeded by Caligula, appealingly played by John McEnery as a tyrant--at once comic and chilling--who gives new meaning to evil in his quest for divinity. He is also unpredictable. In one scene, he gathers his mighty legions on the seashore for an invasion, gives them a pep talk and then inexplicably orders them to gather stones on the beach.

Richard Kiley is a convincing Claudius (though less so than was Derek Jacobi in the 1977 BBC production of “I, Claudius” on “Masterpiece Theatre”), cowering behind a curtain in terror of being assassinated, only to learn that he is the murdered Caligula’s successor.

And lastly there is Nero, broadly and often amusingly played by Anthony Andrews as a sort of fey, limp-wristed villain who schemes even against his incestuous mother and blames Christians for the burning of Rome. (Sorry, he doesn’t play a fiddle.)

When these Roman exotics are cavorting on the screen, “A.D.” is energetic and intriguing. When they are not, “A.D.” is a brick.

Despite some fine acting by Denis Quilley as the apostle Peter and some other nice performances, the birth of Christianity here is a tortuously slow and agonizing dramatic process.

Well before being thrown to the lions in “A.D.,” the Christians fall victim to languid storytelling and poor pacing. Moreover, Christian characters rarely go anywhere unaccompanied by swells of pretentious music, and most of them are so flawless as to be unbelievable.

The 13-episode “I, Claudius” was far less ambitious, giving only the Roman perspective of the times as drawn from a controversial and sometimes fanciful social history by Robert Graves. Yet its comparison with “A.D.” is inevitable.

Whereas the costly and lavish “A.D.” is often ponderous, the low-budget, studio-bound “I, Claudius” had continuous verve and style. Whereas “A.D.” has a handful of strong performances, “I, Claudius” had many that were remarkable, including Jacobi in the lead, John Hurt as Caligula and Sian Philips as the poisonous Livia.

“A.D.” may be the biggest and prettiest. But “I, Claudius” remains the best.