An "overwhelming majority of countries" fail to respect the rights of humanists, atheists and the non-religious according to a new report published today.

The barbarity of Islamic State and the murders of humanist bloggers in Bangladesh are among the persecution meted out to atheists and agnostics this year. Other cases include Ashraf Fayadh in Saudi Arabia and Mohamed Cheikh Ould Mkhaitir in Mauritania, both sentenced to death for apostasy.

The spate of murders of humanist bloggers in Bangladesh by Islamists is detailed in the Freedom of Thought Report 2015, the fourth edition of the survey produced by the International Humanist and Ethical Union with input from the British Humanist Association

Others include the Egyptians, Sherif Gaber, sentenced to a year's hard labour and Karim al-Banna, sentenced to jail for three years.

Some countries have made positive moves, such as Iceland and Norway who abolished their blasphemy laws. In others the situation is deteriorating, with violent attacks on the non-religious by members of the public in countries such as the Maldives.

The report looks at how the non-religious individuals are treated because of their lack of religion or absence of belief in a god. It lists countries with laws that deny atheists' right to identify, revoke their right to citizenship, restrict their right to marry, obstruct their access to or experience of public education, prohibit them from holding public office, prevent them from working for the state and criminalise criticism of religion. In the worst cases, the non-religious can be executed for leaving the religion of their parents. Many deny the rights of atheists to exist.

Atheists, humanists and other non-religious are growing in number worldwide. A 2012 WIN-Gallup survey found religious people make up nearly six in ten of the world's population, while those who identify as atheist make up 13 per cent and a further 23 per cent identify as "not religious".

The report says discrimination against the non-religious is often caused, not by a desire to hurt atheists, but by the desire to help one or more religion. "The promotion by the state of religious privilege is one of the most common forms of discrimination against atheists," it says.

For example, in Lebanon the system of government is based on sectarian quotas, with different rights and roles available to Sunni Muslims, Shiite Muslim and Maronite Christians. "This practice not only codifies and encourages religious discrimination but it also discourages people from leaving the religion of their birth, because they will lose all the state privileges that come with belonging to that religion," says the report.

Rafida Bonya Ahmed, a Bangladeshi blogger who survived an attack, writes in the report: "My late husband, Avijit Roy, was a science author, a blogger, a writer on topics including the origins of the whole universe, homosexuality, the evolution of love and everything including literary criticism in between. Above all he was a humanist. He always wanted to explore the biggest questions in life. His interests were wide, but it was his books on liberal views, faith and disbelief for which he began receiving death threats."

She was a fellow blogger and writer with a published book, Evolution of Life. She writes: "At the International Book Fair in Dhaka in February 2015 we were attacked by a group of men with machetes. Avijit was killed and I sustained four head stabs and a sliced of thumb."

Referring to the spate of murders of non-religious bloggers, she continues: "Dozens more writers who dare to write critically about fundamentalism and advocate for a humanist worldview are receiving death threats, and given the range of those killed so far any of them could be next."

Instead of convicting even one suspect in these killings, the police and government have been threatening to arrest bloggers themselves if they "hurt religious sentiments" by professing their own secular views, she says. "These killings are one part of the problem of extremism in one part of the world, and our freedoms of thought and expression are under attack in many other ways and in many other places around the globe. If there are lessons the world must draw from Bangladesh in recent years, they are these: Allowing bigotry and extremism to fester unchallenged will have generational consequences."

BHA chief executive Andrew Copson, who is also the president of IHEU, said: "Last year we recorded a rise in hate speech and rhetoric: presidents saying humanism and liberalism were a threat to the state, laws branding atheism as terrorism, and so on. This year we've seen that rhetoric bubble over into truly malicious acts of persecution.

"Our ongoing concern is that with jihadist extremism setting the bar very high for brutality, it is creating a space for this deepening, noxious hatred against the non-religious in a growing number of countries, primarily Islamic states. It's almost as if there's this false need to create an equal, imaginary threat from the opposite end of the belief spectrum, as a kind of false balance to the likes of ISIS. In fact this strategy is sometimes almost completely explicit, as in Egypt's war on atheism for example. This entirely misplaced reaction against the non-religious is turning to increasing violence by non-state actors, and ever harsher, transparently unjust sentences from state authorities."