The Vatican is a totalitarian state and, uniquely in the world, an absolute one. It does not have United Nations membership. In a necessarily pragmatic world, that does not mean we should exclude dialogue with it. However, as Bruce Haigh has pointed out, Rudd’s approach is hardly appropriate.

Being a decent bloke is not enough qualification for Tim Fischer in that job. He held the post of Australia’s Minister for Trade; but we have no trade arrangements with the Vatican, nor are there likely to be any. He is not uniquely qualified in Vatican affairs, where division exists in relation to many matters especially in relation to the rights of women, rather than the Vatican, to control their own fertility.

Considerable doubt exists about Tim ever enhancing his qualifications.
In fact Tim would be counter-productive in that post. As facilitator of the Crawford Conferences held at Parliament House, he has expressed the notion that continued increase in human numbers was not an issue deserving attention. That is a matter of grave importance to the world in general, and to women themselves. It is one upon which the Catholic Church is divided, and upon which the fallibility of Papal decree is increasingly flagged by the otherwise faithful.

Unfortunately, this action by Rudd in relation to representation at the Vatican has all the indications of enhancing the unhelpful aspects of Papal influence upon Australian society. There is no prospect that it will progress the interests of Australian voters. It follows the lead of the 2020 summit, which had no relevance other than voter-massaging.

I think the reason for such arrangements between the Vatican and Nation States is based on the historical use of CONCORDATs. http://en.wikipedia.org/wiki/Concordat

The implication of this is is that the signatory Nation State gets the tacit suppport of the Church and all it's followers (ie no active resistance, interference or official political protest) and the Church retains it's power and privilege in that Nation State.

As well as the ones generally known to the public, there are many others that remain secret and not open to public scutiny.

Maybe not a particularly sinister arrangement but historically not an entirely healthy one either.
http://www.concordatwatch.eu/showkb.php?org_id=858&kb_header_id=752&order=kb_rank%20ASC&kb_id=1211