"All reasonable people will agree that there is scope in a secular democracy for reasonable accommodation of religious beliefs when that accommodation does not affect the rights and freedoms of others."
The four Christians turned to the European Court of Human Rights in Strasbourg, France, after losing every round of their battles through the British legal system.
Their claims were filed under European human rights law, focusing on guarantees of freedom of religion and freedom from discrimination at work.
The cases have been closely watched in Europe because they may help to draw a clear boundary in cases where religious views contradict laws against discrimination. The court's decisions have implications across 47 countries on the continent.
The court ruling will not be binding in Britain, but the country is legally obliged to take it into account.