Half of British adults do not believe in evolution, with at least 22% preferring the theories of creationism or intelligent design to explain how the world came about, according to a survey.

The poll found that 25% of Britons believe Charles Darwin's theory of evolution is "definitely true", with another quarter saying it is "probably true". Half of the 2,060 people questioned were either strongly opposed to the theory or confused about it.

The Rescuing Darwin survey, published to coincide with the 200th anniversary of Darwin's birth and the 150th anniversary of the publication of On the Origin of ­Species, found that around 10% of people chose young Earth creationism – the belief that God created the world some time in the last 10,000 years – over evolution.

About 12% preferred intelligent design, the idea that evolution alone is not enough to explain the structures of living organisms. The remainder were unsure, often mixing evolution, intelligent design and creationism together. The survey was conducted by the polling agency ComRes on behalf of the Theos thinktank.

A spokesman for Sense about Science, an independent charitable trust, said it was important for scientists and educators to disentangle religious belief from evidence.

James Williams, a lecturer at Sussex University, said: "Creationists ask if ­people believe in evolution. Evolution is a theory and a fact. You accept it because of the evidence. What the creationists have done is put a cloak of pseudo-science to wrap up their religious belief."

Later this month scientists and academics from across Europe will meet in Dortmund, Germany, to discuss evolution and creationism. It will be the first European conference of its kind to deal with different aspects of attitudes and knowledge related to evolution. They will discuss specific difficulties regarding the acceptance of evolution theory in their home countries.

Williams, who will give a paper presenting a British perspective on evolution and creationism in school science, said: "Evolution is very badly taught in schools so the results of the survey don't surprise me. On the other hand, creationism has traditionally been an issue in North America and there is a big problem in Australia and Turkey. It matters if people don't understand how science works."

The Rescuing Darwin project includes the launch of Darwin and God, a new book on the naturalist's religious beliefs, at Westminster Abbey, where he is buried, and a debate about evolution and religion. Participants will include Dr Denis Alexander, Lord Robert Winston, Professor Steve Jones and Professor Nancy Rothwell.

Events celebrating Darwin's achievements are taking place throughout the year. Cambridge University is hosting a festival to unravel themes of science, society, literature, philosophy, theology and music arising from his writings, life and times.

The Natural History Museum, in London, is exhibiting previously unseen specimens and artefacts, while Darwin's home in Kent, Down House, opens to the public from 13 February.