In a sober ceremony in Rome's Villa Madama, Cardinal Secretary of State Agostino Casaroli and Italian Prime Minister Bettino Craxi signed the new concordat treaty on 18 February 1984.
The top Vatican diplomat with the Roman collar and the socialist prime minister with the red tie made history.
They adapted the Lateran Concordat signed by Mussolini in 1929 to the conditions in democratic Italy and the new self-image of the post-conciliar Church.
In doing so, they placed state-church relations in the country with the largest number of Catholics in Europe on a new footing.
"The state and the Catholic Church are each independent and sovereign in their own order. Both are committed to mutual cooperation for the promotion of humanity and the common good," said Casaroli, summarising the spirit of the agreement. Religion and church are a "social reality in a pluralistic society".
No longer dependent on state authorisations
For the church, this meant a new autonomy with rights and duties - and with relief: It was now no longer dependent on state authorisations, for example in personnel matters. Since then, the church leadership has been free to appoint bishops without having to ask the state.
And senior pastors no longer had to swear an oath of allegiance to the state.
Instead of the 45 articles of 1929, the new concordat comprised just 14, and some of the requirements had simply become superfluous, such as the prescribed prayer service for the king.
The consequences of the Council were more far-reaching, such as the opening up of religious freedom or the Church's relations with the state.
Article 1 of the Lateran Treaties, according to which "the Catholic, Apostolic and Roman religion is the only religion of the state", was therefore obsolete.
Very soon Italy also concluded agreements with the Waldensians and other communities.
The "sacred character" of the Eternal City of Rome - as the episcopal see of the Pope and centre of the Catholic world - established by the Lateran Concordat "in the name of the Most Holy Trinity" was also obsolete.
It was now succinctly stated that Italy recognises "the special significance that Rome has for Catholics as the Pope's episcopal see".
Legacy of the Lateran Treaties
The 1984 treaty nevertheless retained essential parts of the Lateran Treaties. These had ended the enmity between the Holy See and the Italian unitary state, which had occupied the Papal States in 1870, in 1929.
The Lateran Treaties had created the sovereign Vatican State and compensated the Pope for the loss of the Papal States. In return, the Pope recognised the Kingdom of Italy with its capital Rome and declared the territorial conflict settled.
Religious education was reorganised in 1984. Previously a compulsory subject, attendance is now optional.
In principle, the convention on marriage law was retained, according to which - unlike in Germany - church marriages are valid under civil law.
A type of "church tax" was also introduced: the 0.8 per cent levy, which is also mandatory for non-members of the church, can be donated to the church or other charitable causes.
The response to the revision of the concordat was initially divided. Some saw it as the glorious conclusion of the secular state foundation initiated in the Risorgimento of 1870, as Craxi emphasised at the signing ceremony.
Others saw it as an "instrument of harmony".
Praise from Benedict XVI
Benedict XVI later praised the "healthy secularity" with which the revision had contributed to cooperation in a pluralistic society and guaranteed religious freedom. Francis also spoke of a "positive secularity".
They share fundamental values on topics such as human dignity, family, solidarity and peace and work together for the good of the country.
Although not all state-church conflicts in Italy have been resolved, both sides today praise the good cooperation - which is now even evident in criminal proceedings. His ministry would not be possible "without the generous availability and cooperation of the Italian state", said Francis soon after taking office.
Conversely, Italy always finds the "best ally" for the promotion of society in the Church.
The Vatican and Italy are also dependent on this cooperation with regard to the next major joint project: When 35 million pilgrims are to come to the Eternal - but no longer Holy - City of Rome for the Holy Year 2025.