Tunisia has seen several firsts in recent years. It was the first country to revolt in the Arab uprisings, the first to overthrow its leader, the first to hold democratic elections. And now another - it has the first major Arab Islamist party to formally announce the separation of religion and politics, and declare itself part of "Democratic Islam".

The Ennahda party, despite being rooted in the Muslim Brotherhood, says it will separate its religious activities from its political branch, and that its mosques will be politically neutral.

The annual party congress overwhelmingly approved the move, and party leader, Rached Ghannouchi, (exiled under the Ben Ali dictatorship) went so far as to tell Le Monde: "We are leaving political Islam and entering democratic Islam.'

For an Islamist this is a quite an intellectual, political and theological journey to have made. All their teaching insists that Islam is a complete system in which the political and religious worlds are one. There are no entities to separate, and nothing in their scripture approaching the Christian tenet "Render unto Caesar what is Caesar's, and to God what is God's."

If Mr Ghannouchi is sincere, and enough Tunisians believe him, Ennahda has a chance of regaining power in the 2019 elections. In 2014 it lost the election and co-operated in a peaceful transfer of power to a caretaker government of technocrats.

The leader has had two examples to inform his decision. In Egypt, after the Muslim Brotherhood won the 2012 parliamentary and then presidential elections, it went too far and too fast in implementing religious authority in various walks of life. They alienated the population to the extent that many welcomed a second military coup in 2013. (The first being the overthrow of Mubarak in 2011). By contrast, in Turkey, President Erdogan's AKP party is preparing to reveal again what it was at the beginning - a Muslim Brotherhood influenced movement.

As Mr Erdogan has rolled back freedoms and weakened the secular foundations of the Turkish state, Western democracies have fallen out of love with what they called the "Turkish Model". If Ennahda returns to power, and it is the largest bloc in Parliament, there may be a "Tunisian Model".

If so, is it to be trusted? That is for the Tunisian people to judge. They know that Islamist theologians are quite clear that it is permitted to dissemble, indeed to fool, the "enemies of true Islam" by being temporarily pragmatic. They also know that Mr Ghannouchi has always been among the deeper, relatively liberal, and yes, pragmatic, of the Islamist thinkers of the last few decades.

And finally they know that Tunisia has proportionality sent more fighters to join Daesh than most Arab countries. The storms blowing through the region are far from over. Even if Mr Ghannouchi is dissembling, and he may well not be, better a long, peaceful march through the institutions than the violent Islamist nihilism of the jihadists. Better still, a long march to genuine "Democratic Islam".

Tim Marshall is a former Sky News diplomatic editor