It seems that in Dasher's fantasy world, a religious individual could not have committed such an act. Never mind that there have been instances of people killing their children because they believed the children would go to a better place; or that there have been thousands upon thousands of murders committed by religious believers throughout history (just as there have been countless murders committed by atheists); or that the Bible itself has God commanding people to do things comparable to the Sandy Hook massacre. No, in this fantasy worldview only those convinced that human beings are entirely physical beings can be mass murderers.
And how does Dasher even know what the madman responsible (who incidentally was brought up religious and even attended a religious school) believed?
At any rate, there isn't one bit of evidence that atheists regard human life as having no value – and for a very good reason: believing that we are physical beings has no bearing whatsoever on how we should treat one another. What Dasher and those like him need to get through their physical skulls is that for a nonbeliever, what human beings are composed of and how they got here is morally irrelevant. Neither having a non-physical part nor being created by a god would make human beings one iota more valuable. It is only in the minds of people like Dasher that such things are seen as significant.