While Mr. Muggeridge and the Bishop's harangues can be quite tedious to get through at times, the whole thing is interesting because of how well they obliviously make Cleese and Palin's point for them. As Cleese futilely tries to tell them, the point of the movie isn't to ridicule the figure of Christ, it's to ridicule "closed systems of thought." The film is meant to encourage people to think for themselves, to approach matters—including religion—with an open mind and critical thinking. Mr. Muggeridge and the Bishop do an excellent job of showing the pitfalls of such closed systems by clearly having had their opinions of the movie set in stone before they ever saw it and by stubbornly brushing off all of the Pythons' attempts to explain to them how they'd misinterpreted the film.
You can find the second part of the video and the rest of my thoughts below the fold. (By the way, ignore the titles of the embedded videos. :P They were clearly uploaded by another person who isn't keen on listening to what the Pythons were actually saying.)