Michael Corleone: I feel I'm getting wiser now.
Kay Corleone: The sicker you get, the wiser you get, huh?
Michael Corleone: When I'm dead, I'm gonna be really smart.
Michael Corleone: Your enemies always get strong on what you leave behind.
Michael Corleone: Friends and money - oil and water.
Michael Corleone: Never let anyone know what you are thinking.
Michael Corleone: Never hate your enemies. It affects your judgment.
Michael Corleone: Just when I thought I was out, they pull me back in.
Answer: Michael is trying to divest the family of all ties to organized crime. Internazionale Immobiliare is an international real estate concern and owning it would legitimize the family, making them respectable landowners. Michael is attempting to buy out the Vatican's 25% of the shares in it to gain controlling interest, but the other families either want in on the deal or want to steal it out from under him, forcing him back into his old criminal ways.
Captain Defenestrator