The return of intolerant religious faith is the biggest challenge facing the world in the 21st century and as important as climate change, President Nicolas Sarkozy of France said on Friday.

In a speech to foreign ambassadors in Paris, Mr Sarkozy said the “return of religion in most of our societies” was a reality and that “only sectarians do not see it”. The difficulty, he said, was ensuring that a religious revival did not come in the form of fundamentalist, closed and exclusive faiths.