preposterous |prɪˈpɒst(ə)rəs|, adjective contrary to reason or common sense; utterly absurd or ridiculous: a preposterous suggestion.

The danger of religious faith is that it allows otherwise normal human beings to reap the fruits of madness and consider them holy because each new generation of children is taught that religious propositions need not be justified in the way that all others must.

Civilisation is still besieged by the army of the preposterous. We are even now killing ourselves over ancient literature.

Sam Harris in The End of Faith Sessions 2