I used to wish the Church's infallibility claim be downgraded to just a claim of authority, since I can understand authority, it being a purely human thing and more easily believed. But then I realized that if the Church taught, for instance, that Jesus wasn't really God, then the gates of Hell had, in fact, triumphed.
And then there's also a nice parallel between Christ and His Body as Peter Kreeft points out in his conversion story:
The parallel between Christ and Church, Incarnation and Church history, goes still further. I thought, just as Jesus made a claim about His identity that forces us into one of only two camps, His enemies or His worshippers, those who call Him liar and those who call Him Lord; so the Catholic Church's claim to be the one true Church, the Church Christ founded, forces us to say either that this is the most arrogant, blasphemous and wicked claim imaginable, if it is not true, or else that she is just what she claims to be. Just as Jesus stood out as the absolute exception to all other human teachers in claiming to be more than human and more than a teacher, so the Catholic Church stood out above all other denominations in claiming to be not merely a denomination, but the Body of Christ incarnate, infallible, one, and holy, presenting the really present Christ in her Eucharist.He also had a good line in this: "I think that in Heaven, Protestants will teach Catholics to sing and Catholics will teach Protestants to dance and sculpt." I can country line-dance, that's about it.