If God really could have protected those children but chose not to as a means of teaching us a lesson because we dared to keep institutional prayer out of public schools, what about that is worth worship? Is an omnipotent deity that opts not to intervene to save innocent children from violent, painful, terrifying death truly a God of love and forgiveness, or is He a God of wrath? And if the latter, what reason other than fear of reprisal is there to worship?
If God does not have the ability to intervene and couldn’t have stopped the massacre even if He wanted to, then what does it matter that He is “not welcome” in public schools? If He cannot intervene, then welcome or not, prayer or not, their fate was in the shooter’s hands, not God’s, wasn’t it?
Simply by virtue of offering an explanation for why God permitted this atrocity, are people not presuming to know God’s mind and intent? If He is angered by human arrogance in the separation of church & state, would He not also be angered by the arrogance of this presumption?

I have no quarrel with people who seek refuge in prayer to cope with this or any tragedy; we all must grieve and attempt to make sense of things in our own way, and if God serves that purpose for some, then who am I to argue? However, when fundamentalists begin laying blame for such events at the feet of secular laws and assert that their God could do better, it is fair to require them to demonstrate how, precisely, He would do so. Subjecting their proposals to the scrutiny of critical thought, starting with answers to these questions, seems both reasonable and right. In a world where six- and seven-year-olds are shot to death for no reason, a little more reason and rightness seem in order.