US Vice President Joe Biden visits this week a small nation in Europe that has done more than most to find space for belief and tolerance.

Biden, a devout Catholic, is going to Kosovo and then Serbia, and he will find that in the Western Balkans religious politics are as passionate and important as anywhere in the world.

In the Balkans, the Muslim Ottomans, Orthodox Russians, and Christian Austrian-Hungarian and German imperial powers squabbled for centuries leaving behind after 1945 an artificial construct – Yugoslavia – nominally atheistic and which collapsed the moment communism ended and a wily Catholic-born Croat wheeler-dealer, Tito, was replaced by a ultra-nationalist Serb, Milosevic, of Orthodox faith who in less than a decade saw eight nations remove themselves from rule by Belgrade.

Two nations – Slovenia and Croatia both with strong Catholic traditions – have made it into the EU. The others, including Orthodox Serbia, Montenegro and Macedonia along with Muslim Kosovo and the mixed community that is Bosnia, are still waiting in the queue to join fully the European family of nations.

The mid-wife of this spring-time of new Balkan nations was the United States and especially Joe Biden who condemned the Milosevic doctrine of Serb supremacism and in the US Senate and then as Chair of the Senate Foreign Relations Committee insisted that Serb ultra-nationalism should not prevail.

The medieval style siege of Sarajevo followed by the Serb massacre at Srebnenica in 1995 and then the ethnic cleansing of 850,000 Kosovans four years later who fled for the hills or over borders rather than risk Serb genocidalists, changed public opinion. But Biden was already the global spokesperson for supporting freedom from Serb rule in the West Balkans even if the political-judicial structures set up in the new nations were pitifully ill-equipped for the task.

He got first hand reports from his son, Beau Biden, like his father a Delaware lawyer who served in the army and spent a year in Kosovo in 2001 training lawyers and judges. Biden junior came home to rise in state politics with every chance of making a national political career when he suddenly died from brain cancer in 2015. His mother had been killed in a car accident in 1972 when Joe Biden was elected at age 30 to be the youngest ever senator in America.

Many politicians have family tragedies to live with but for Vice President Biden to lose wife and then son seems an unfair curse from fate.

In Kosovo, Biden will unveil a stretch of a highway named after his son and meet Kosovo's leader, President Hashim Thaci, a convinced Americanophile. Thaci has just returned from the Rio Olympics where he saw the Kosovan Majilinda Kolmendi win a gold medal for judo.

Thaci like most Kosovans is a moderate Muslim. The nation's capital has its mosques but also young women wearing the shortest mini-skirts in Europe and the great Peja beer, one of the finest brewed in Europe, together with Kosovo wines that suggests that Islam in Kosovo is tolerant and modern.

Thaci was leader of the Kosovan Liberation Army but made sure it protected all Orthodox churches and monasteries during the 1998-1999 war of liberation. Unlike the Serb military and death squads who claimed they were protecting the Orthodox faith from Muslims, Thaci, who was educated in Switzerland, insisted that no imam or any expression of Islam should be part of his movement.

He has cooperated closely with US and European intelligence and police agencies to stamp down hard on any efforts to set up Islamist preaching cells or recruit young Kosovans for jihad.

The biggest faith building in Kosovo is the giant Mother Teresa cathedral in Pristina and Thaci and other Kosovan leaders regularly visit Rome to be received at the Vatican. Thaci thinks he has Catholic ancestors and Biden will not be short of churches or chapels of his faith on his visit.

Each summer Kosovo hosts a major inter-faith conference for the entire region and Serb Orthodox monks, English Anglicans, imams and Jewish rabbis spend a weekend sorting out their problems in the Kosovo mountainside.

Winning an Olympic gold medal should be a good moment for Kosovo but just as the tiny nation was celebrating its Olympic glory the prime minister of Serbia, Alksander Vucic, stood up in the Belgrade Parliament and referred to Kosovo as a "southern Serbian province." Earlier in the year the president of Serbia, Tomislave Nikolic, refused to join all other Balkans leaders at Thaci's inauguration as president by stating that Kosovo "did not exist as an independent state."

Biden travels to Serbia after Kosovo and will encounter the surreal nature of Balkan politics in which countries pretend that their neighbours do not exist. The two Orthodox EU states, Greece and Cyprus, also refuse to recognise Kosovo's existence in part out of solidarity with their Orthodox cousins in Belgrade.

Can Biden knock any sense into his Serbs hosts? Unlikely. Bismarck famously said that the Balkans were not worth the bones of a single Pomeranian grenadier. Today as the West Balkan route from Greece to northern Europe of so many refugees and economic migrants as well as Islamist ideologues is well travelled one would think Europe might get its Balkans act together and lean on Belgrade to stop playing pretend games and accept that Kosovo is no more going to return to rule by Serbs than Ireland was ready to return to rule by the English after 1921.

So far, Serbia has not managed to win a single Rio medal and the sight of the Kosovan team boasting a gold is now doubt galling in Belgrade. Vladimir Putin backs Belgrade against Joe Biden and the US support for Kosovo. But Biden's visit is a reminder that the West Balkans is Europe's unfinished business and if the EU cannot sort out its own backyards how can it claim to be a serious geo-political player?

And when Biden retires are there US politicians ready to invest time and commitment in helping the West Balkans?

Denis MacShane is a former Minister for Europe who travels regularly to the Balkans.