One in four Brits think it's not possible to be both British and Muslim, according to the 2013 British Social Attitudes survey.
The survey, carried out by social research agency NatCen, also found Britons overwhelmingly believe you must speak English and be born in the UK to be considered British.
But the most startling finding is that almost one quarter of the population still thinks a person can only be British if they are Christian, meaning they don't think Muslims, Jews, Hindus, Sikhs or Atheists can be considered British.
In the past however a larger proportion of the population thought a person could only be British if they are a Christian. In 1995, 32% of the population thought this to be true.
The survey also found that 95% of Brits think you can only be "truly British" if you speak English and nearly three in four Brits believe you must be born in the country to be British. Half the population also said that a person could only be British if they shared British traditions, a percentage that has not changed since 1995.
The British Social Attitudes survey has been conducted annually since 1983. It asked more than 3,000 respondents about various issues, including national identity, immigration and the Scottish independent referendum.