He reached into his rucksack and said with a smile, “I have something for you.” I extended my hand and took the gift. A small book, 96 pages – a Bengali translation of Am I a Monkey?: Six Big Questions About Evolution by the Spanish-American evolutionary biologist and philosopher Fransico J Ayala. I looked at the illustration on the cover: a sad ape evolving into a human.

One of the translators of the book, Ananta Bijoy Das, was hacked to death by machete-wielding assassins in May 2015, outside his home in Sylhet, north-eastern Bangladesh. The other translator, Siddhartha Dhar, was standing in front of me, somewhere in Stockholm. A few months after the murder of his friend and mentor, Siddhartha left Bangladesh and is now in exile in Sweden. Translating a book on evolution is a dangerous business sometimes.

Ananta Bijoy Das (1982–2015) was a prophet of freethought who, in 2005, first organised a small group of freethinkers in Sylhet (which happens to be my home-town). Most of them were students of the Shahjalal University of Science and Technology, named after a sufi saint credited for the spread of Islam in the region in the fourteenth century.

Ananta and his comrades had a different mission: spreading scientific knowledge and propagating rationalism in one of the most religiously conservative corners of the country. They organised study circles; translated influential and critical texts on science, pseudo-science, religion, sexuality, politics and world history; wrote essays that challenged systems of social, political or religious oppression; and, published a journal titled Jukti (rationality, logic). They were also part of Muktomona (freethinker), a larger network of Bangladeshi freethinkers founded by the Bangladeshi-American author Avijit Roy.

These, of course, were activities that angered lots of people. Homoeopathy practitioners threatened to sue the editors and writers of Jukti for publishing articles that exposed the pseudo-science behind their trade. Many people were offended by essays critical of Hinduism. Many more were uncomfortable with taboo-breaking discussions on sexuality. When Ananta wrote a book about pseudo-science in the Soviet Union, that ticked off the authoritarian left.

The most vocal opponents, however, were the Islamist students of the science and technology university. They had their own mission: propagating neo-orthodox Islam. Many of them were members of Hizb ut-Tahrir, the pan-Islamist political party. While the freethinkers were translating the works of authors like Fransico J Ayala, the Islamists were busy spreading the gospels of Salafi preachers like Zakir Naik and Bilal Philips.

Across Bangladesh, a battle of ideas was going on between the freethinkers and the Islamists – a battle that mostly took place over the Internet, in weblogs and discussion forums. In this battle, people like Ananta Bijoy Das and Avijit Roy were manning the fort of freethought. It was under their leadership, freethinkers in Bangladesh were challenging the forces of ignorance and obscurantism. And, in this war of words, they were winning.

Sometime around 2011, another group of Bengali translators started organising themselves in some hidden corners of the Internet. To this day, if one looks closely, some signs of those early days can be found in different places – in abandoned weblogs, Facebook groups, image-hosting websites and cached pages available via the Internet Archive. These were Bangladeshi Islamists who had graduated from vanilla Salafism to the next level. They wanted to become the holy warriors of Islam by enlisting themselves as the footsoldiers of the global jihad. In preparation of this jihad, they translated hundreds of jihadi documents into Bengali: sermons, fatwas, communiques and martyrdom stories. Then, in early 2012, they took a name: Ansarullah Bangla Team. Thus, a new jihadi group was born on the Internet.

In the real world, the founder of Ansarullah Bangla Team was Jashimuddin Rahmani, a mufti who delivered the khutbah-e-Jumuah (Friday sermon) at a mosque in Dhaka (the Bangladeshi capital). He was one of the most influential Salafi preachers in the country, whose neo-orthodox interpretation of Islam attracted hundreds of young men to the mosque.

Rahmani’s disciples were mostly students from different private universities in the city. Many of them were former members of Hizb ut-Tahrir, banned by the Bangladesh government as a terrorist organisation in 2009. It was under the guidance and leadership of Rahmani, they were now trying to link themselves up with another terrorist organisation: al-Qaeda. Translating important al-Qaeda documents into Bengali was the first step towards that goal.

It was in May 2012, Ansarullah Bangla Team published a Bengali translation of The Dust will Never Settle Down, a lecture by the Yemeni-American imam and al-Qaeda ideologue Anwar al-Awlaki, who was killed in a US drone strike in 2011. It remains one of the most influential sermons the imam ever delivered, outlining the theological basis for brutal and merciless assassination of blasphemers and apostates – in other words, anyone accused of insulting Muhammed or deviating from the diktats of Islam.

al-Awlaki’s genius was in that he produced the blueprint of a new form of jihad, in which purely intellectual ventures like a French satire newspaper (Charlie Hebdo) or a Bengali weblog (Muktomona) became legitimate military targets. It of course was quite a feat that he, from beyond his grave somewhere in Yemen, became the spiritual leader of a group of highly-motivated assassins in a faraway country like Bangladesh.

And, it is in Bangladesh, al-Awlaki’s followers are now slaughtering freethinkers like Ananta Bijoy Das and Avijit Roy. Their only crime was engaging in critical discussions on religion and exposing the systems of religious oppression. Since February 2013, at least ten intellectuals and activists have been assassinated across the country. All of them were hacked to death by machete-wielding young men: members of Ansarullah Bangla Team/Ansar al Islam. The latest victims were Xulhaz Mannan and Mahbub Tonoy, slaughtered inside Xulhaz’s home in Dhaka on April 25. Two courageous LGBT rights activists, fighting for gay rights in one of the most homophobic societies in the world – two martyrs in the struggle for freedom and human rights.

Will this struggle go on even when the list of the martyrs keep growing? I asked Siddhartha, as we were walking through the streets of Stockholm. “They will never be able to scare us into silence. When we signed up for this, we knew there would be threats against our lives. We accepted it as a fact,” he told me. The fact, of course, is that freethought can never be assassinated.

A German version of this article was first published in the Jungle World.