Küng belajar [[teologi]] dan [[filsafat]] di [[Universitas Kepausan Gregoriana]] di [[Roma]] dan [[ditahbiskan]] pada []. Kemudian ia melanjutkan pendidikannya di berbagai kota Eropa, misalnya di [[Universitas Paris|Sorbonne]] di [[Paris]]. Tesis doktoralnya berjudul "''[[Pembenaran]]. Doktrin [[Karl Barth]] dan sebuah refleksi Katolik''".
<!--In [] Küng was appointed [[professor]] of theology at [[Eberhard Karls university|Eberhard Karls University]], [[Tübingen]], [[Germany]]. Just like his colleague Joseph Ratzinger (later [[Pope Benedict XVI]]), in [] he was appointed ''peritus'' by [[Pope John XXIII]], serving as an expert theological advisor to members of the [[Second Vatican Council]] until its conclusion in []. At Küng's instigation, the Catholic Faculty at Tübingen appointed Ratzinger as professor of dogmatics. However, due to the fact that Ratzinger moved in a more conservative direction in the reaction to the [] [[German student movement|students revolt]], cooperation between the two came to an end.
In the late 1960s Küng became the first major Roman Catholic theologian after the late [[ 19th century]] [[ Old Catholic Church]] schism to reject the doctrine of [[ papal infallibility]], in particular in his book ''Infallible? An Inquiry'' ([]). Consequently, on [[ December 18]] , [], he was stripped of his license to teach as a Roman Catholic theologian but carried on teaching as a [[ tenure]] d professor of [[ ecumenism| ecumenical theology]] at the University of Tübingen until his retirement (''Emeritierung'') in []. To this day he remains a persistent critic of papal authority, which he claims is man-made ( and thus reversible) rather than instituted by [[ God]]. He was not [[ Excommunication| excommunicated]] and remains a Roman Catholic priest.
In the early [[1990s]] Küng initiated a project called ''Weltethos'' (''Global Ethic''), which is an attempt at describing what the world religions have in common (rather than what separates them) and at drawing up a minimal code of rules of behaviour everyone can accept. His vision of a [[global ethic]] was embodied in the document for which he did the initial draft, ''Towards a Global Ethic: An Initial Declaration''. This Declaration was signed at the [] [[Parliament of the World's Religions]] by many religious and spiritual leaders from around the world. Later Küng's project would culminate into the [[UN]]'s "Dialogue among Civilizations" to which Küng was assigned as one of 19 "eminent persons." Even though completed shortly after the terrorist attacks of September 11 (in November 2001), there was no coverage in the U.S. media, something about which Küng complained.
Based on "Studium Generale" —lectures at Tübingen University, his latest publication ''Der Anfang aller Dinge'' (" The beginning of all things") discusses the relationship between [[ science and religion]]. In an analysis spanning from [[ quantum physics]] to [[ neuroscience]] he also comments on the current debate about [[ evolution]] in the United States, dismissing those opposed to evolution as " naive [ and] un-enlightened". -->
Pada [[26 September]] [] ia terlibat dalam suatu diskusi bersahabat tentang teologi Katolik dalam sebuah makan malam bersama Paus Benediktus XVI -- sesuatu yang mengejutkan sejumlah pengamat.