He took part as an expert in the Second Vatican Council and was a consultor to the then-Council for Dialogue with Non-Believers, participating in colloquiums around the world.
In 1986 he was appointed a member of the International Theological Commission and became its secretary in 1989.
In 1990, he was nominated Theologian of the Pontifical Household. He has also served as president of historical-theological commission of the organizing committee of the Grand Jubilee of the Year 2000. Presently, he serves as director of the journal Nova et Vetera (Geneva), founded by Cardinal Journet.
Preconized Cardinal, was elected to the titular Church of Tullia, with personal title of Archbishop, on 7 October 2003 and consacrated on 20 October.
Theologian emeritus of the Pontifical Household, 1 December 2005
Created and proclaimed Cardinal by John Paul II in the Consistory of 21 October 2003, of the Deaconry of Ss. Domenico e Sisto (Sts. Dominic and Sixtus).
Judas was appointed by Jesus.