Pope Benedict has approved a new text asserting that Christian denominations outside Roman Catholicism are not true Churches in the full sense of the word.
The document, issued by a Vatican watchdog, has been criticised as offensive by some Protestants.
The text was written by the Vatican's Congregation for the Doctrine of the Faith, headed by Pope Benedict before his election as Pope.
It states that Christ established only one Church here on earth.
Other Christian denominations, it argues, cannot be called Churches in the proper sense because they cannot trace their bishops back to Christ's original apostles.
The new text is basically a re-statement of another document known as Domine Jesus, published in the year 2000 under the signature of the then Cardinal Joseph Ratzinger, now Pope.
That document set off a storm of criticism from Protestant and Anglican leaders who felt that the Vatican was failing to take into account progress made towards re-establishing Christian unity in talks with Rome over a period of many years.
Gee, and here I was thinking that being a Protestant meant you didn't want to sign off on what the Catholic Church says.