Half way though this book and it is AWSOME! I had read quotes by Russell and knew of his reputation but had never read anything by him. This is a collection of diverse pieces by Russell about religion, written at various stages of his life. Even though the earliest pieces were written nearly 100 years ago, it still seems very fresh, and he clearly anticipated much that has since come to pass.
Recently there has been much talk of defending Christianity against the onslaught of atheists such as Richard Dawkins and Christopher Hitchens. The idea is that overt and uncompromising expressions of atheism are a new development. I think these people should read what Russell wrote in the 1930's. It's a clinical and intellectual demolition of belief in God and organised religion, such as Dawkins (though not perhaps Hitchens or Grayling) could not hope to match.
I recommend you read it, whether you are confirmed Christian or Atheist. It's surely beneficial to be well informed, whatever your personal views...
There's a synopsis on Wikipedia at: http://en.wikipedia.org/wiki/Why_I_Am_Not_a_Christian