The problem is that many liberals cannot conceive of evil outside of not recycling.Too many tepid Christians of the modern era cannot fathom what evil looks like. They are unable to categorize anything as evil; this leads to tremendous discomfort with the actions such as the London bombings. If there is no evil, then, somehow, the bombings must be justified. Logic is tortured beyond all recognition in the effort to keep evil from being correctly identified.
They cannot express righteous indignation at the action. That would require they take a moral position; that would be unacceptable in their non-judgmental world.