A few posts below I raise the question whether the claim of the Roman papacy to be 'the Vicar of Christ' is well founded. This question needs to be asked because it is both an exceptional claim (if true we ought to order the life of the global church accordingly) and a controversial one (remember: it is not just Protestants who do not accept it; Eastern Orthodox reject it).
Let's begin by acknowledging what is unexceptional and non controversial about the office of the Bishop of Rome: among bishoprics it is ancient, eminent, and has a distinctive claim to have begun with the Apostle Peter himself. (It is controversial to move beyond 'distinctive claim' to 'historical fact'). Further, the global church organised in such a manner that the Bishop of Rome is the Pope of the largest church (here I mean the Western rite Catholic church) and the largest communion of churches (here I mean the Western rite Catholic church united with the Eastern rite churches in full communion with the Bishop of Rome) is impressive. It lives according to a coherent theology, faithfully orthodox in very many respects accepted by other churches (here I am speaking as an Anglican, so our church is one of those churches; but viewed with Roman eyes we are an 'ecclesial community'). Perhaps the most impressive achievement of the papacy, to a Protestant, or for that matter to an Eastern Orthodox Christian, used to churches in dispute with other churches, is that it sits at the apex of this very large global church (or, if you will, church of churches) which manages, somehow, to be an exemplar of unity-in-diversity.
It is quite understandable that the impressive achievement of the Roman church over the centuries, indeed millenia has developed two unfortunate capacities concerning the papacy. One is to present the papacy as divinely special: this is the Vicar of Christ with plenipotentiary powers to speak the mind of God infallibly. Another is to continually avoid facing certain historical facts, namely the errors and immoralities of past popes which belies and undermines the claim to being divinely special. There is even, many would argue, a present fact which undermines such a claim: the slowness of the papacy to recognise and then resolutely deal with recent misdeeds of clerics. The tendency of the papal led hierarchy of the church to act slowly, if not to even cover up the abusive behaviour of priests is understandable (but inexcusable) as an expression of the fallibility of human nature. This tendency has occurred in other churches, though many of those churches woke up to their fallibility at least a decade before Rome has. What seems very difficult to explain - I suggest, I can just about imagine some comments which will be made! - is how any person claiming to hold the office of 'Vicar of Christ' could oversee the church of Christ with so many past and present mistakes.
Just to head off one set of imaginable comments in response: I quite understand that the 'infallibility' of the Pope is deemed to refer to a special set of circumstances in which the Pope (in reality after significant consultation, reflection, and maybe even centuries of prior theological discourse) pronounces on some matter and declares it to be infallible, in distinction from other matters on which the Pope speaks and does not declare it to be infallible. My point here is that this amounts to special pleading in respect of the role of 'the Vicar of Christ': it is reasonable to expect that every pronouncement of the Vicar of Christ is as though Christ himself were speaking, and Christ speaks infallibly! In sum, the Pope is not the Vicar of Christ. The history of the papacy does not support this theological claim.
In my view this does not make much difference to the strength of the constant claim from Rome that in any future configuration of churches into one unified, global church, the Bishop of Rome must have 'primacy.' Reasons for that insistence can be mounted on the basis of the ancientness of the bishopric, its status as the preeminent bishopric in the world, and the like. (Think about this: if all Christians voted in a world Christian parliament for this or that bishop to be the 'primate' of a world church, then, presuming Roman Christians did not feel any great persuasion in arguments in favour of (say) Canterbury or Moscow or Antioch, the voting would be overwhelmingly in favour of the Bishop of Rome being the primate!!)
Not that I expect Benedict XVI to agree with me any time soon (!!), but if he did, then what might be different is in Roman attitude to other churches and ecclesial communities. Recognition of the fallibility of the papacy could go hand in hand with a new appreciation of the fallibility of other churches and ecclesial communities, leading to a changed estimation of ecclesial communities, and of 'orders' of ministry currently not recognised. The ecumenical outlook could be as changed as Canterbury weather is when the wind swings from the south to the north-west (i.e. warmer).