This comment is the best I've seen so far regarding the Boston tragedy. It comes from retired Anglican Bishop the Rev. Steven Charleston. It was posted on my friend Dale McNeil's page.
"Why? Why the pointless cruelty, O God? Why the premeditated evil that comes to bring death, pain and sorrow to innocent lives and leaves us stunned to imagine a heart so cold it could conceive such an act? We cannot understand it, God, we cannot make sense of the senseless. And how should we respond even if we did understand? Tooth for tooth, eye for eye, would it end the madness or return the lost to live again? Come, Spirit of God, come stand with us in this darkness. Hold the fallen in your arms. Heal the injured. Comfort the broken-hearted. And if you cannot tell us why we do this to ourselves, show us how to love more deeply, that such pain will never be the final word, but rather mercy that needs no explanation."