[2] Ordained as a priest on 29 October 1933 by Cardinal Francesco Marchetti-Selvaggiani, he originally served as a chaplain and teacher during World War II, his main concern at that time being youth ministry.

This was an unexpected action on the part of John XXIII, who had been advised to withhold the red hat from König due to the unclear legal situation of the Church in Austria: the Austrian coalition government, on the insistences of Social Democratic Party ministers, refused to accept the concordat negotiated between the Holy See and Chancellor Engelbert Dollfuss's Austrofascist government.

By 1958 the newly appointed Cardinal König had managed to convince the authorities in Austria to recognise the earlier regulations in a new treaty, which was signed in 1961.

The two top candidates, conservative Giuseppe Siri and liberal Giovanni Benelli, both faced too much opposition to win the papacy.

[5] He was mainly concerned with questions of ecumenism, however also serving as president of the Vatican Secretariat for Non-Believers (which in 1993 was united with the Pontifical Council for Culture) from 6 April 1965 until his resignation on 27 June 1980.

He was an advocate of reform at the Second Vatican Council (1962–1965), serving on its preparatory commissions and greatly contributing to its declaration on non-Christian religions, Nostra aetate.

He opposed Austrian legislation on abortion, whilst at the same time describing the publication of Pope Paul VI's encyclical condemning contraception, Humanae vitae, as being a "tragic event".

Despite securing the election of John Paul II, his relations with the Holy See turned somewhat sour toward the end of his tenure as Archbishop of Vienna.

König criticized the Pope for refusing to engage with what he considered "the spirit of progress that the Second Vatican Council had developed"[citation needed] and disagreed with what he perceived to be an overly centralised Church and too much control in the hands of the Roman Curia.

The Curia also appeared to display hostility toward König, refusing to back his suggested candidate for Archbishop of Vienna—Bishop Helmut Krätzl, an auxiliary bishop of Vienna.