Russell Blackford and Udo Schuklenk at Comment is Free (linked here at AlterNet) say that atheists have a duty to mock religion when religion plays too big a role in the political sphere.
The writers say:
Enlightenment thinkers such as Voltaire often used mockery to show the absurdity of ideological stances — including religious ones — that were considered sacrosanct. Mockery is one way of saying that a view does not deserve to be taken seriously. Religious views are fair game if one can also show, on a more serious level, why the view in question does indeed not deserve serious respect.