... why the papal attempt to cause schism within Anglicanism is likely to undermine Rome's ecumenical attempts (link). I don't endorse or even like Kung. He's a Roman Catholic priest, whose authority to teach theology has been revoked by the Vatican (as of 1979, I believe). Back in the 60's he used to work with Joseph Ratzinger, who is now the pope of Rome, though plainly the two have parted ways in certain respects. Kung is considered a theological "liberal" in Roman Catholicism today. His area of specialty: ecumenical theology.
His view of Christianity is far too broad. Christianity is to be defined by the gospel as preached by Jesus and the apostles: a gospel of repentance from sin and trust for salvation in Christ alone.
Kung's complaints are somewhat revealing, however. They demonstrate the fact that, for Rome, unity with those she considers "other Christians" must always be subservient to her goal of maintaining primacy over the church.
Kung states: "Evidently, the papal primacy – which Pope Paul VI admitted was the greatest stumbling block to the unity of the churches – does not function as the 'rock of unity'."