In part II of Fahrenheit 451, Faber says that Christ has basically become what now?
What Faber says about Christ is that Christ has become "part of the family." When he says "family" he means the families that are in the shows that are on the parlour walls -- like the ones that Millie Montag is so into. He goes on to say that Christ has been essentially turned into an advertising tool.
Basically, what has happened is that the society has taken all the meaning out of Christ and out of religion. It is only using him for the materialistic purposes that are so important to the society. Like everything else, he has been dumbed down and used for society's own purposes.