Another quote from Mencken (p. 380 in the Notebooks) showing that he was indeed the first New Atheist:
One of the most irrational of all the conventions of modern society is the one to the effect that religious opinions should be respected. …[This] convention protects them, and so they proceed with their blather unwhipped and almost unmolested, to the great damage of common sense and common decency. that they should have this immunity is an outrage. There is nothing in religious ideas, as a class, to lift them above other ideas. On the contrary, they are always dubious and often quite silly. Nor is there any visible intellectual dignity in theologians. Few of them know anything that is worth knowing, and not many of them are even honest.