Not always separate fields of knowledge, today science and religion seem to be at each other's throats.

"Science without religion is lame, religion without science is blind." Albert Einstein, 1941.

In pre-modern societies, science, medicine and religion were intertwined. Natural phenomena were understood in spiritual terms and human disease and illness were seen as manifestations of the will of spirits and gods. Understandings of illness based on nature and the gods continued to complement one another into the modern era and the role of priest and healer was one and the same.

At the same time, the growth of medicine often depended on the corresponding emergence and spread of organised religions. Christianity taught that the human body belonged to God and had to be properly looked after. In the European 'Dark Ages' of the early medieval period, medical knowledge and expertise was concentrated in ecclesiastical institutions such as monasteries, which also frequently provided healthcare to the local population. When secular hospitals were built in later centuries, they always contained chapels.

The emphasis on purity and cleanliness in Hinduism, Judaism and Islam ensured that personal care and hygiene were central to faith. In the 800s and 900s CE, the world's most advanced hospitals were in the cities of the Islamic world, while Greek and Roman medical knowledge was being absorbed and developed by Islamic scholars.

Even as medical understanding grew in sophistication during the Renaissance period, spiritual explanations for disease were still widely believed, and spiritual remedies still sought. Jews, Christians and Muslims all carried amulets to ward off evil spirits. Christians directed prayers to specific saints for specific illnesses. St Luke, author of one of the Christian gospels, is traditionally believed to have been a physician, and has therefore become the patron saint of physicians and surgeons - as well as of butchers.

However, religion has often been antagonistic to the establishment of science as a separate worldview. Galileo was tried and sentenced to house arrest by the Roman Catholic Inquisition for his assertion of the Copernican view that the earth rotated around the sun, rather than the Church's orthodoxy that the earth was the centre of the universe. In the 19th century, many Christians were strongly opposed to Darwin's theory of evolution, and some evangelical Christians, particularly in the USA, still reject evolution in favour of creationism. Christian churches have also opposed human dissection for fear of the consequences when the body was resurrected. Today, some faith groups believe particular medical interventions are wrong, and many Jehovah's Witnesses reject blood transfusion. Genetic manipulation, and in particular stem cell research continue to provoke calls for caution from religious leaders.

From the 1800s, as the intertwined traditions of medicine and religion began to separate, an increasingly secular medical establishment developed. Modern medicine and modern science appear to be incompatible with, and even in opposition to, religion. Religion relies on revelation and belief, while science relies on observable, repeatable experience. Indeed Sigmund Freud considered religion to be a form of mental illness. The most high profile recent example of the conflict between religion and science has focused around the writings of evolutionary biologist and 'militant atheist' Richard Dawkins. However, there has also been growing academic interest in the relationship between religion and health and some studies have shown that spirituality - including prayer, meditation and attendance at religious services - can benefit health.