The plot was stolen from ...
If you liked the idea of fake evangelists, you might like "Elmer Gantry".
It was made in the fifties, but is only a little dated because of differences in lighting and makeup style. It was set in the twenties, and is the movie version of a book of the same name by Upton Sinclair. Lancaster's character is a small time hustler and traveling salesman who joins a large and succesful revival service.
The plot is more subtle and deeper than LOF's. It's one of those movies that makes you question the way you look at things. Nothing is as simple as it seems. Or is it? Was Gantry a hustler or really a man of faith? Is there a difference?
I liked both movies and hesitate to say one is better than the other, except to say that EG is better written. Sinclair was "somebody", you know...
Enjoy.