In 2004 Cardinal Ratzinger, the future pope, spoke out against letting a Muslim state join, although at the time the Vatican was formally neutral on the question.
Later when Cardinal Ratzinger became Pope Benedict XVI, the Vatican officially cooled on the question of Turkish membership, but still did not oppose it outright, insisting only that the Copenhagen criteria, including freedom of worship, be fulfilled.
But he did not expect the demands on religious freedom to be fulfilled: "One great fear is that Turkey could enter the EU without having made the necessary advances in religious freedom. [Parolin] insisted that EU members – and the US – continue to press the [Turkish government] on these issues … He said that short of 'open persecution', it couldn't get much worse for the Christian community in Turkey."
It's a pity that the Pope isn't willing to be more candid publicly about his feelings on Turkey. In particular, his views might carry some weight in Poland which, faithful American lackey that it is, has been one of the most fervent proponents of Turkish accession.
No doubt recalling the reaction to his speech in Regensburg deters him from speaking more openly. There the Pope simply quoted a 13th century text, which said:
Show me just what Muhammad brought that was new and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached.
Muslims across the world showed their quality by rampaging, burning, defiling and killing in response. In fact, our Turkish friends, the Directorate of Religious Affairs (Diyanet) no less, petitioned to have the Pope indicted and arrested on his upcoming visit to Turkey. The grounds cited, apparently without irony, were that by delivering his speech he had infringed "freedom of thought".
The cables yet again show the Americans lobbying for Turkish accession to the EU, even at the Vatican, despite the revelations in other cables that they, too, feared about the growing strength of Islamic consciousness within Turkey. Apparently inflicting this problem on the Europeans is just fine by them.
The cables reveal the American government lobbying within Rome and Ankara for Turkish EU membership. "We hope a senior department official can visit the Holy See and encourage them to do more to push a positive message on Turkey and integration," concluded the 2006 cable.