The International Humanist and Ethical Union (IHEU), a global body comprising atheists, agnostics and other religious sceptics, has said that a majority of countries discriminate against atheists.
The Freethought Report says that there are laws that deny atheists' the right to exist, curtail their freedom of belief and expression, revoke their right to citizenship and restrict their right to marry.
"This report shows that the overwhelming majority of countries fail to respect the rights of atheists and freethinkers although they have signed UN agreements to treat all citizens equally," said IHEU President Sonja Eggerickx.
The study was led by lawyers and human rights experts who looked at statute books, court records and media accounts to detect discrimination in 192-member states of UN.
The report also claims that non-believers are discriminated against even in North American and European nations. In the US, "atheists and the non-religious are made to feel like lesser Americans or non-Americans", the study says.
The IHEU says there is a systematic or severe discrimination against atheists in many states of the European Union.
According to the report, Latin American and the Caribbean countries except Brazil faced systemic discrimination. In Brazil the situation was "mostly satisfactory", while Jamaica and Uruguay are judged as "free and equal."
In 13 of the Muslim countries around the world, people who espouse atheism or reject the official state religion of Islam are beheaded.