That's strange. I had never heard that the Hitton Gibson was involved in the marketing. It would be especially stange if he was involved in getting Vatican approval, since he's a vehement critic of the Vatican and may not believe they are legitmate.
You can find his interview here. That may well have been hot air. I presented it as an example of why, in my opinion, Hutton's views should have been confronted at the time of the film. He was implying involvement, and frankly his newfound publicity was solely because of the controversy surrounding the film. I wouldn't attribute Hutton's views of the Vatican as Jewish occupied territory or the Pope as illegitimate to Mel, but one states that he learned his faith from his father, it becomes a rather obvious question.