Hans Küng (German: [ˈhans ˈkʏŋ]; 19 March 1928 – 6 April 2021) was a Swiss Catholic priest, theologian, and author.

[1] He published Christianity and the world religions: paths of dialogue with Islam, Hinduism, and Buddhism in 1986, wrote Dying with Dignity together with Walter Jens in 1998, and signed the appeal Church 2011, The Need for a New Beginning.

At the invitation of Karl Barth, he delivered a lecture on the prospects for reform of the Catholic Church—he was very optimistic—just a week before Pope John XXIII announced his plans for a council in January 1959.

[4] In 1962 he was appointed peritus by Pope John XXIII, serving as the youngest (34) expert theological advisor to participants in the Second Vatican Council until its conclusion in 1965.

At Küng's instigation, the Catholic faculty at Tübingen appointed another peritus, Joseph Ratzinger, the future Pope Benedict XVI, as professor of dogmatic theology.

[b] It identified a number of areas of agreement between Barthian and Catholic theologies of justification, concluding that the differences were not fundamental and did not warrant a division in the Church.

In this book Küng argued that Barth, like Martin Luther, overreacted against the Catholic Church which, despite its imperfections, has been and remains the body of Christ.

[11] Veteran newsperson Patricia Lefevere,[12] writing for the National Catholic Reporter, says the Holy Office "opened a secret file (the infamous 399/57i) on Küng shortly after he wrote [this book]".

[17] Lefevere writes that:[4] In Disputed Truth, [the second] of his three volumes of memoirs, Küng spent 80 pages reviewing charges against him — secret meetings by German bishops and Vatican officials outside of Germany, betrayal by seven of his 11 Tübingen colleagues, and a near physical and emotional breakdown caused by exhaustion from his efforts to answer Vatican accusations while preserving his place in a state university.

[4] In the early 1990s, Küng initiated a project called Weltethos ("Global Ethic"), which is an attempt at describing what the world's religions have in common (rather than what separates them) and at drawing up a minimal code of rules of behaviour that everyone can accept.

[25] Years later when the possible beatification of Pope John Paul II was under consideration, Küng objected that his was "an authoritarian pontificate which suppressed the rights of both women and theologians".

[16] On 26 September 2005, he had a friendly discussion over dinner at Castel Gandolfo with Pope Benedict XVI, avoiding topics of obvious disagreement and focusing instead of Küng's interreligious and cultural work.

[29] The pope acknowledged his efforts to contribute to a renewed recognition of crucial human moral values in dialogue between religions as well as with secular reason.

[30] In a 2009 interview with Le Monde, Küng sharply criticised Pope Benedict for lifting the excommunications of four bishops of the Society of Saint Pius X.

"[35] His fellow theologian Charles Curran, who had experienced similar treatment by the Vatican, described Küng as "the strongest voice for reform in the Catholic Church during the last 60 years" and wrote that he was so prolific that "I do not know of anyone who was ever able to even read all that he had written.

[38] In 2005, Küng published a critical article in Italy and Germany on "The failures of Pope Wojtyla" in which he argued that the world had expected a period of conversion, reform, and dialogue but, instead, John Paul II offered a restoration of the pre-Vatican II status, blocking reform and inter-church dialogue, and reasserting the absolute dominion of Rome.

[39] Based on his Studium Generale lectures at Tübingen University, in Der Anfang aller Dinge (The beginning of all things) he discussed the relationship between science and religion.