"Science without religion is lame, religion without science is blind." So said Albert Einstein, and his famous aphorism has been the source of endless debate between believers and non-believers wanting to claim the greatest scientist of the 20th century as their own.

A little known letter written by him, however, may help to settle the argument - or at least provoke further controversy about his views.

Due to be auctioned this week in London after being in a private collection for more than 50 years, the document leaves no doubt that the theoretical physicist was no supporter of religious beliefs, which he regarded as "childish superstitions".