a year after its foundation in 1990, Ratzinger joined the European Academy of Sciences and Arts in Salzburg. Ratzinger defended and reaffirmed Catholic doctrine, including teaching on topics such as birth control, homosexuality, and inter-religious dialogue. The theologian Leonardo Boff, for example, was suspended, while others such as Matthew Fox were censured. Other issues also prompted condemnations or revocations of rights to teach: for instance, some posthumous writings of Jesuit priest Anthony de Mello were the subject of a notification. Ratzinger and the congregation viewed many of them, particularly the later works, as having an element of religious indifferentism (in other words, that Christ was "one master alongside others"). In particular, Dominus Iesus, published by the congregation in the jubilee year 2000, reaffirmed many recently "unpopular" ideas, including the Catholic Church's position that "salvation is found in no one else, for there is no other name under heaven given to men by which we must be saved." The document angered many Protestant churches by claiming that they are not churches, but "ecclesial communities". Ratzinger's 2001 letter De delictis gravioribus clarified the confidentiality of internal church investigations, as defined in the 1962 document Crimen sollicitationis, into accusations made against priests of certain crimes, including sexual abuse. This became a subject of controversy during the sex abuse cases. For 20 years, Ratzinger had been the man in charge of enforcing the document. While bishops hold the secrecy pertained only internally, and did not preclude investigation by civil law enforcement, the letter was often seen as promoting a coverup. Later, as pope, he was accused in a lawsuit of conspiring to cover up the molestation of three boys in Texas, but sought and obtained diplomatic immunity from liability. On 12 March 1983, Ratzinger, as prefect, notified the lay faithful and the clergy that Archbishop Pierre Martin Ngô Đình Thục had incurred excommunication latae sententiae for illicit episcopal consecrations without the apostolic mandate. In 1997, when he turned 70, Ratzinger asked Pope John PaulII for permission to leave the Congregation of the Doctrine of Faith and to become an archivist in the Vatican Secret Archives and a librarian in the Vatican Library, but John Paul refused his assent. Ratzinger engaged in a dialogue with critical theorist Jürgen Habermas published years later by Ignatius Press. Papacy: 2005–2013 Election to the papacy In April 2005, before his election as pope, Ratzinger was identified as one of