A Roman Catholic priest once classed as an enemy of the state will tonight receive one of the world's most prestigious awards.

Czech philosopher and pastor Msgr Prof Tomáš Halík will be presented with the £1 million Templeton Prize at St Martin-in-the-Fields, London.

In a speech at tonight's ceremony he will address questions of multiculturism raised by Prime Minister David Cameron's statement that "Britain is a Christian country", which provoked a furious backlash from humanist campaigners.

He will warn of the limits of the virtue of tolerance, which without genuine encounters between people of different faiths and backgrounds can result in isolationism.

"A certain model of multiculturalism based on the principle of tolerance resulted not in a community of citizens, or neighbours, but in a conglomeration of ghettoes," he will say.

He will argue that "a model of multiculturalism based on the principle of tolerance can work for people living alongside each other, but not for people living together", and ask: "How can the power of faith create respect, where differences are not perceived as threats but as potential for mutual enrichment?"

He will also warn about the dangers of Russian nationalism and policies of national selfishness and isolation. If the European Union collapses, he says, the nation states of Europe will not acquire greater sovereignty, but instead would be exposed to forces of chaos and destruction from within.

Leading members of the Czech and UK Catholic community, Czech political and cultural leaders, along with other senior British faith leaders, will attend the ceremony.

Prof Halík, 65, was labelled an "enemy of the regime" by the Communist government of the then Czechoslovakia after delivering a speech at his doctoral graduation in 1972 urging the need for truth after Soviet forces had crushed the Prague Spring. With an academic career seemingly barred, he became a counsellor and therapist to alcoholics and drug addicts but worked to build up an "underground university" of philosophers and theologians who prepared for a new democratic era.

His work as a priest and theologian was shaped by his experiences under communism, which taught him the need for dialogue and encounter between people of different faiths and none.

Now Professor of the Sociology of Religion in the Department of Religious Studies at Charles University in Prague, he is also pastor of the Academic Parish of Prague. He credits the discrimination he faced under communism for his commitment to learning from other Christians.

Interviewed on the award of the Templeton Prize to him, he recalled that the government's strategy was to "divide and rule". "Protestants opened up possibilities for Catholics, so there were Bible circles for young people and they invited us to participate," he said. "For me, it was the chance to learn more about Protestant theology and how they interpret the Bible and for my Protestant friends I was able to offer something from the Catholic tradition. We could enrich each other. Structure was not so important."

He has also sought to build bridges with non-believers and in his role as pastor of the Academic Parish of Prague has had a significant evangelistic ministry, baptising more than 1,000 adults. According to Prof Halík, the number of dogmatic atheists in his own country is decreasing. Referring to the story of Zacchaeus, who observed Jesus from a distance until invited to join him, he said: "The world is full of Zacchaeuses, who are keeping their distance: but Jesus Christ is calling them by name. My life's mission is to communicate with the Zacchaeuses."

He also spoke of the importance of acknowledging doubt, saying that faith and doubt were "two sisters". "Faith without question is fundamentalism. We need an inner dialogue between faith and critical reason.

"When speaking with unbelievers, I ask them, what does this God look like in whom you don't believe? Then I tell them, I don't believe in him either. It is a caricature of God."

Prof Halík is the 44th recipient of the Templeton Prize, established in 1972 by the late global investor and philanthropist Sir John Templeton. Former laureates include the Rev Dr Billy Graham (1982), Aleksandr Solzhenitsyn (1983) and Martin Rees (2011). Last year's recipient, Desmond Tutu, followed the 2012 Templeton Laureate, the Dalai Lama.