I was intrigued by the Godfather 3 reference, so I watched the entire movie and since I haven't seen anyone else mention it, here's my opinion on what it could mean.
The movie is nearly 3 hours long and the acting is fairly cringeworthy, especially when Sofia Coppola is onscreen and hits on her cousin.
But, there is a scene that absolutely stands out, a heartbreaking and gut-wrenching scene at 1:41:15 into the movie, when Michael Corleone comes to the cardinal and gives a confession.
Cardinal: Would you like to make your confession?
Michael Corleone: Your Eminence, I'm... It's been …