Religious scepticism This notion has been around for thousands of years, eg “Primus in orbe deos fecit Timor” - “First of all in the world Fear created the gods” (Petronius a Roman contemporary of Jesus). Moreover, well before WW1, such an explanatory rejection of institutional religion was current in the UK as elsewhere.
The impact of the war on religious belief  Although for some the war was accompanied by strengthening of their existing religious resolve, for others the opposite happened. For them the nature and extent of human suffering defied belief in any possible God who is loving and fair. And this view was further reinforced by the massively extensive ’flu epidemic of 1918-19.
Theodicy Philosophers of religion refer to this challenge to religious belief as ‘Theodicy’ – how might believers resolve the problem of suffering? Others don’t bother any more with institutional religious language or debate – that’s all past its sell-by date and is simply irrelevant.
http://www.newworldencyclopedia.org/entry/Theodicy