Why I Am Not a Christian and Other Essays on Religion and Related Subjects - Bertrand Russell, Paul  Edwards
Why is "New Atheism" called new? As far as arguments specifically directed against religion, I can't recall anything said recently that Russell (and many others) didn't already say in the first half of the century. However, there are many other topics covered in this book, and that's where plenty of room for disagreement comes in. In particular, his idea of psychology seems very debatable to me. He's convinced that all competitiveness and aggression could be eliminated by a simple program of positive childhood education, for one thing. His optimistic view of human nature is the basis for confidence in social progress, aided by scientific progress.

Russel was a fine writer, and not only are his arguments clearly stated, but he puts them into vigorous words. There is much that's memorable here. Perhaps the most eloquent essay of all, which remains completely relevant, is "Freedom and the Colleges", written just after moral guardians had successfully used the courts to prevent Russell from teaching at the City College of New York.