If you are forbidden to voice the hard questions, this might suggest that faith survives only by never being challenged. The person who actually expresses their fury or disgust or disillusion can, at least sometimes, be demonstrating faith of a sort, confidence that, if God is real, it is possible, even necessary, to say what you feel about Him – and that, unless you can say this, the God you started with is not worth believing in. This underpins many of the Jewish Psalms or the poems of George Herbert or Gerard Manley Hopkins. Blasphemy resists the conspiracy of silence about the agonising difficulties of belief, resists the stifling of a real and honest response to an unjust world.

Source: Rowan Williams: the case for blasphemy