Bangladeshis are not secular and very religious be it Muslims, Hindus, Buddhists or Christians.
However though religious, Muslims of Bangladesh are not fanatic or extremist. In Bangladesh Durga Puja, Christmas and Buddha Purnima are celebrated with the same zeal as Eid.
If one visits Bangladesh during Durga Puja you can see how big the celebration is. Hindu, Buddhist, Christian festivals also has been recognised as public holiday.
If you go to other countries even the Western nations you will not find such scenario. Basically we are religious but we don't meddle into the affairs of other religious groups and let them celebrate as they wish.
However since the last 6-7 years or so extremism both liberal extremism and Islamic extremism is growing in Bangladesh.
Liberal extremism in Bangladesh are basically Atheist bloggers, Taslima Nasreen type lady, LGBT etc. Islamic extremism however is spreading through facebook. You will find radical preachers or Facebook pages like Noyon chatterjee who abuses Hindus, Buddhists, Christians etc.
Even there are Bangladeshis who say that Amar Sonar Bangla is Haram because it was written by Hindus.
Facebook is to be blamed for this rising chaos. Both liberal and religious extremism.