The "evil" of the terrorists' actions in the Russian school massacre has tested even the Archbishop of Canterbury's faith, he has admitted.
The siege at a school in Ossetia ended in a bloodbath on Friday
It would be inhumane not to question one's beliefs, Dr Rowan Williams told BBC Radio 4's Today programme.
"I think it is probably the suffering of children that most deeply challenges anybody's personal faith," he said.
"When you see the depth of energy that people can put into such evil, then... there is a flicker, there is a doubt."
"It would be inhumane, I think, not to react that way."
But he insisted the murdered children had not been abandoned by God, who had given humans freedom to make decisions and did not intervene, even in acts such as this massacre.
He quoted Jesus as saying it would be better for people who committed offences against children to have millstones put around their necks and be cast into the sea.
"They were performing perhaps the most evil kind of action that we can imagine," he said.
He called for the terrorists to be jailed for life but did not want to see them given death sentences.