Hans Küng, a Catholic theologian and philosopher, was born in 1928 in Sursee, Switzerland. After completing his preliminary studies, he traveled to Rome, the heart of Catholic Christianity, to pursue philosophy (1948-1951) and theology (1955-1955) at the Pontifical Gregorian University. During this period, he wrote two dissertations: one in philosophy examining Jean Paul Sartre’s atheistic humanism, and the other in theology exploring Karl Barth.

In 1951, he traveled to France to pursue a PhD in theology. He furthered his philosophical and theological studies at the Catholic University of Paris and Sorbonne University. Upon completing his PhD in theology, he returned to Lausanne, Switzerland, and was ordained as a priest. In 1960, he accepted an invitation from the University of Tübingen in Germany to become a professor of theology, a position he held until his retirement.

In 1962, he was appointed as a theological advisor to Pope John XXIII. In this role, he had the opportunity to influence important decisions, such as shedding light on the theological perspectives of Church officials, and played a crucial role in shaping the Second Vatican Council (1962-1965).

In 1963, Hans Küng founded ecumenical theology with the aim of fostering closer relationships between Christian denominations, and eventually various religions. This initiative led to the establishment of the Institute for Ecumenical Research. Since then, his scholarly and practical endeavors have focused on promoting unity among diverse religions around the world.