The Web caters to niche markets as easily as it does to mainstream tastes. Will it help extreme religious groups achieve unprecedented prominence? An important thesis for the future of the Web, particularly for e-commerce, is Chris Anderson's long-tail theory. In the language of economics, the traditional marketplace best satisfies the bulge of the normal demand curve, where most consumers congregate, thanks to economies of scale. In this article, we examine this theory with regard not to an economic market, but rather to the competitive marketplace of ideas. In a religious context, we interpret the long-tail theory as predicting that the Web will allow extreme or strict sects to flourish in an unprecedented way by helping proponents cater to the long tail online. If this is true, it threatens the orthodox understanding of the dynamics of religious extremism. It would also undermine the associated idea that groups' convergence on the middle ground of religious beliefs cultivates and is cultivated by liberal civic virtues. If radical groups can flourish while preaching virtues diametrically opposed to liberalism, freedom of religion might not be so good for liberalism after all.