In the context of European integration, the great French Christian philosopher Jacques Maritain and his influence on the European project in the mid-20th century are mentioned very rarely. This paper seeks to shed some light on his somehow hidden role in this context, especially given the central role of freedom of conscience within the personalist philosophical heritage to which Maritain belonged and the political philosophy he shaped, which had a key impact on the European project and its basic documents. Freedom (...) of conscience is seen here as the cornerstone of all human freedoms despite all the risks and complications that this entails. In all conflicts between the State and the conscience, it is necessary and desirable to always go in favour of the conscience or at least to lean towards political solutions that respect or at least do not despise the conscience of the person. Whenever we face seemingly unsolvable problems in such conflicts, dialogue and negotiation should always be chosen instead of violence and imposition. (shrink)