BOB Simans (Letters, October 8) claims that atheism is at the very centre of communism, while moderation and tolerance are found at the core of each religion. He does not compare atheism and religion on equivalent terms, since atheism is placed (questionably) at the centre of communism, while religions are pictured as having centres. His comparison is thus really between entire religions, which are mostly moderate, and communism: a political extremity.

If we make the more meaningful comparison between communism and religious extremism, and ask what is at the centre of the latter, we could justifiably answer "religion", for movements like Isis are just as religious as communism was atheistic. Mr Simans is correct that fanaticism is not the key to faiths, but faith is the key to various examples of fanaticism, and it's easy to see why.

The Abrahamic faiths posit an all-powerful ruler of the universe who demands unique worship and complete obedience from mankind and dishes out eternal reward or punishment accordingly. This ultimate dictator never appears or speaks directly, so must be represented on earth by people who claim to know his will. Such a belief is bound to produce fanaticism in a portion of believers.

Robert Canning,

Vice-chair of The Scottish Secular Society, 58a Broughton Street, Edinburgh.