Islamist movements in Bangladesh supported the Pakistani regime, they wanted to keep the two countries merged together as a single Islamist entity. Most of the folks in these movements where people possessing religious authority such as mullahs and imams.
Eventually Bangladesh did manage to break away from Pakistan forming into its own country in 1971. Not the best in the world but I'd say a lot better than Pakistan with its blasphemy laws and other figures of Islamism in power, plagued by the Taliban, etc.
The Pakistani sympathizers, the people of the Islamist "right" planned to usurp power and failed but nonetheless survived trial and weren't punished for their war crimes until now. The problem? These Islamist figures indoctrinated the youth to believe that there is a conspiracy against Islam in our country and they are being punished not because of their war crimes but they're framed for being Muslim.
Think of the evangelical complains of war against Christianity here in the US and multiply times hundred with guns and thugs involved. On one hand you have a growing population of youths who think there is a conspiracy against Islam, some kind of religious oppression. They want to wage war, jihad, against the so-called kuffar powers who are fueling this conspiracy against Islam from the West and from India.
These guys are relentless. They support everything that has to do with violent jihad, the misguided kind: ISIS, Taliban, all that stuff. They want a caliphate, the only way, they believe, they can stop this conspiracy and oppression of Muslims in their own land.
On the other hand, you have the hedonists, the anti-theists, using this opportunity to vilify Islam as a violent, misogynistic, homophobic, anti-freedom, anti-democratic, tyrannical ideology against all notions of culture and civilization that must be eradicated in order to restore peace.