On the one hand, you have the Christians, or Xians if you want to be more extreme. They seem nice enough people, young and old, a bit bellow the poverty line; all they really want to do is hang out together in secret meetings to sing the praises of peace, love, and Jesus. Then along comes the pesky intolerant Romans, who shoot arrows at the worshippers and send them to the colosseum. There, they face being squished by elephants or eaten by crocodiles and lions, in between the acts involving boxing, gladiators and women battling pigmies.
The pagan Roman nobles, which populate this film, by comparison, have it great! Parties all the time, all the grapes one can gobble, with more sexy bisexual prostitutes than you can shake a stick at (all right, you only see one, but there has to more out there in ancient Rome). Add Claudette Colbert (as Nero's horny wife Pomepea) bathing in the milk of donkeys, and you know that they are always having a grand old time.
Why the film's hero, Prefect Marcus Superbus (Fredric March, looking very superb in a short tunic and perm), should convert in the end and join his pious Xian girlfriend (Elissa Landi) in being lion chow, is a little perplexing. He enjoys having fun with his fellow Romans, enjoying life and not giving a damn what the next day will bring. In comparison to that, the Xians are the ultimate party poopers, preferring to talk of salvation and not partake in more sinful delights.
So After spending more than 2 hours seeing him having a ball chilling with his pagan pals and getting chummy with Colbert, it's a bit of a shock for him to give it all up to convert literally minutes before the fateful gate opens. Then again, in addition to having an admittedly to a cute uplifting final shot, the entire film is supported by lovely decor and costumes, and populated by the always enjoyable March, Colbert, and Laughton, I carry more praise than disinterest towards it.
While I doubt that the film ever succeeded in converting anyone besides Marcus Superbus, it sure as hell provides a good, pre-code, sometimes head-straching entertainment.