In the first round of Jakarta's gubernatorial election, held on Wednesday, the incumbent governor Basuki Tjahaja Purnama, commonly known as Ahok, came out on top winning around 43 percent of the ballots cast, according to preliminary estimates. However, he failed to reach the 50 percent threshold required for an outright victory, triggering a run-off election that is due to be held on April 19.

In the second round, Ahok, an ethnic Chinese Christian, will be contesting against former education minister Anies Baswedan, who came second in the first round by securing around 40 percent of the vote and with strong backing from conservative and hard-line Muslims.

Agus Harimurti Yudhoyono, the son of a former president, was a distant third with about 17 percent and eliminated from the contest, but how his supporters vote in the run-off will decide the result.

Many observers view the election as a litmus test for religious tolerance in the world's most populous Muslim country.

Indonesia has seen a spike in communal tensions in recent months due to blasphemy charges leveled at Ahok for apparently telling voters they were being deceived if they believed a specific verse in the Quran prohibited Muslims from electing a non-Muslim as leader.

Although Ahok has always rejected the accusations he insulted the Quran, hundreds of thousands of protesters took to the streets in November and December calling for his arrest, forcing the embattled Jakarta governor to publicly apologize to all Muslims in the country.

Still, the blasphemy issue was seized by his political opponents and dominated the campaign. Both Anies and Agus invoked the Quran and urged Muslim voters to only vote for a Muslim candidate.

In a DW interview, Indonesia expert Susanne Schröter says the political climate in Indonesia is increasingly embittered and that many liberals are scared due to government inactivity in the face of Islamist violence.

DW: How much have the blasphemy allegations leveled against Ahok hurt his re-election prospects?

Susanne Schröter: The allegations have certainly hurt him, with a broad coalition of forces mobilizing against Ahok. At the end of last year, hundreds of thousands of people - under the banner of the Front for the defense of Islam (FPI) - thronged the streets and demanded that he be put in prison for blasphemy. This accusation has in recent years increasingly been used as a political instrument.

Radical Islamist forces in the country have increasingly gained traction in recent years. What are the reasons behind this development?

This is a complex issue that goes back all the way to Indonesia's independence struggle against the Dutch colonizers, and the ranks of those freedom fighters included many Islamist actors.

From the beginning, their aim was to create a post-colonial Indonesia based on Islamic religious law. But Indonesia's first President Sukarno worked ruthlessly against these efforts.

He proclaimed "pancasila" as the state's guiding philosophy. This principle clearly states that Indonesia will not be an Islamic state, but rather be conceptualized as a multi-cultural and multi-religious nation.

This preamble, however, was never really accepted by many of his Islamist companions. Only through stringent authoritarian rule was it possible to keep these discontent powers, which have always been there, under control. But fundamentalist and strongly political Islam has moved back into the limelight since the late 1980s. At the very latest, since the fall of Sukarno's successor Suharto in the year 1998, radical and often violent Islamist groups have been very present in the public sphere.

Schröter: 'There is a big danger here that if these tensions spill over, Indonesia's society will radicalize even further'

How is the Indonesian state responding to these challenges?

Facing pressure from outside, the state is trying to bring these forces under control. This is only partially successful. What the state has not been able to prevent, however, is a strong Islamization of society as a whole since about the turn of the millennium.

It is evident in the way people dress, read Islamic literature and watch movies, among other things. One could argue that everyone should live as they see fit and that this has no effect - the Indonesian constitution allows for this.

However, parallel to the Islamization, one can see an increased pressure on minorities - Christians, Shiites or Ahmaddiyya. There are more and more calls, especially from the FPI, for Indonesia - as the world's largest Muslim-majority country - to become an Islamic state. This process has already gone quite far: many districts and provinces are ruled by Shariah - or Islamic law - as a supplement to existing law. In the Aceh province, one has gone as far as to rewrite all legislation based on Islamic interpretations.

What role have these trends played in the blasphemy allegations against the incumbent Jakarta Governor Ahok?

Up until the year 2004, the blasphemy law in Indonesia had been used only around 25 times. In the last ten years, however, the number has shot up tenfold. So it has become one of the weapons of these radical groups, to carry forward a development that enjoys great popularity and to mobilize against all those that are opposed to it. In the last presidential elections, this was already an important topic, the same goes for these gubernatorial elections.

Despite these developments, Islamist parties have so far played only a minor role in elections. Do you see this changing now? Is "political Islam" becoming more socially acceptable?

The unsettling thing is that although Islamist parties do not enjoy successes at the polls, we see that mainstream parties are increasingly adopting the same agendas.

The adoption of elements of Shariah has almost always been carried out by secular parties.

There has been a takeover, so to speak, of secular parties by Islamist actors. Conversely, one likes to instrumentalize Islam, because there is a strong belief that a candidate's chances are decreased when they are discredited as being un-Islamic.

This you can also see in this electoral campaign. We saw Ahok's adversary Agus Yudhoyono, the son of former President Susilo Bambang Yudhyono, play the Islamic card out of sheer power calculations. Apparently this strategy seems to have at least partially worked.

Ahok is considered to be a close confidant of President Jokowi. How is he positioning himself?

Ahok is someone that is closely tied to President Jokowi. Thus, these attacks are also very clearly targeted at the president but he is letting things run their course. He is trying to act as a mediator and does not want to alienate Muslim voters. However, the fact that he has turned up to more problematic events, that he is not speaking his mind and that people do not know exactly where he stands is now also seen as one of his weaknesses.

Jokowi has been subject to accusations of not doing anything against Islamist violence. Especially the FPI has presented itself as a party that does not fear violence. These are people that destroy bars, disrupt art exhibitions and have taken part in attacks on minorities. All these things the president has refrained to condemn. One does get the feeling that he does not want to stake out a clear position in this debate which is not exactly a sign of strength.

Can this come back to haunt him - perhaps in the next presidential elections in 2019?

The country is truly divided. Indonesia has long been known as a country that practices a tolerant and moderate form of Islam. This still exists. Furthermore, people that speak out for a multicultural Indonesia do exist. But it is these people that are increasingly challenged. During the current gubernatorial election the outcome hangs in the balance. It is difficult to say in which direction the country will go by 2019. What is clear, however, is that the political climate is increasingly embittered and that many liberals are scared due to government inactivity in the face of Islamist violence. Therefore there is a big danger here that if these tensions spill over, Indonesia's society will radicalize even further.

Susanne Schröter is an Indonesia expert and Director of the Research Center on Global Islam at Johann-Wolfgang von Goethe University in Frankfurt.

The interview was conducted by Thomas Latschan.