In 1994 Cushley was summoned to the Pontifical Ecclesiastical Academy, studying diplomacy at the same time as studying for a doctorate in canon law at the Pontifical Gregorian University, which he earned in 1997. He formally entered the Diplomatic Service of the Holy See on 1 July 1997. Cushley has served in the nunciatures of Egypt, Burundi, Portugal and the United Nations in New York and South Africa. From 2009 until 2013, Cushley was head of the English-language section of the Vatican Secretariat of State. In that capacity, he was responsible for accompanying the pope during all his visits to English speaking countries, such as the visits by Benedict XVI to Malta, Cyprus and the United Kingdom in 2010. In 2012, he took on an additional role in the Vatican when he was appointed to the ceremonial position of "prelate of the anticamera", with duties that include assisting when the pope receives visits from prominent dignitaries such as heads of state.
Episcopal appointment
On 24 July 2013 Cushley was appointed as the Archbishop of St Andrews and Edinburgh, less than a year after Cardinal O'Brien resigned over sexual misconduct. On appointment, Cushley stated: Cushley was consecrated and installed on 21 September, the Feast of Saint Matthew, where the principal consecrators were Cardinal James Michael Harvey of the Basilica of Saint Paul Outside the Walls; the Papal Nuncio, Antonio Mennini; and Archbishop Philip Tartaglia of Glasgow. Cushley's assistant responded to one victim of child sex abuse with, "While the archbishop sympathises with your situation, he regrets that he is unable to assist you." Under guidance from the Vatican's Congregation for the Doctrine of the Faith, Cushley banned theologian Tina Beattie from lecturing to a lay Catholic group, the Newman Society, saying that "Beattie was known frequently to have called into question the church’s teaching". In Lent 2015, Cushley outlined his vision for the future of the Archdiocese in a Pastoral Letter entitled "We Have Found the Messiah". The document's stated aim was to "respond to the mission entrusted to him by Pope Francis: to bring the joy of the Gospel to contemporary society." Following the publication of the letter, Cushley embarked upon 32 public meetings across the Archdiocese to discuss his ideas, which include the possibility of creating larger parish units through either mergers or closures. Cushley planned to restart a dormant office dealing with poor and marginalised people. He noted that Francis wants more done for poor people. Cushley wanted to find out fast what the archdiocese does for destitute people, unemployed people, drug addicts and others who are traditionally helped. Cushley wanted to see if improvements were possible. In February 2015 Cushley came under attack in an op-ed article published in the Observer newspaper which noted that the Catholic Church in Scotland had not corporately joined Churches' Mutual Credit Union, a new credit union co-founded by other Scottish Christian denominations. It also called upon Cushley to sell his official residence, St Benet’s, to provide funds for poor people.
Keith O'Brien
stood down as archbishop after three priests and a former priest accused him of predatory and unwelcome sexual contact in the 1980s. In September 2013 "Cushley...suggested that O’Brien will not be permitted to return to Scotland and is likely to spend his remaining years in exile." according to The Scotsman. By contrast the BBC claimed "Cushley conceded it was "not impossible" that the cardinal would one day return. But he made it clear he did not believe that possibility was likely or desirable." Cushley also said he did not believe an independent investigation into O'Brien was necessary. Talking about the situation with O'Brien, Cushley denied that the church was at its lowest ebb though the church and had taken a battering. Cushley said that the people of the Archdiocese wished to leave the matter behind. He also said, "Cardinal O’Brien’s behaviour distressed many, demoralised faithful Catholics and made the church less credible to those who are not Catholic." but called for forgiveness.