In other words it is the basic “Because there is Evil, there can be no God,” argument.
It is always best to get a second opinion on such important matters, however, and so I offer these thoughts of a friend to you for consideration:
"How can evil—that which is absolutely reprehensible under all circumstances—exist in a world without an ultimate good against which to measure? In a world without God, all so called "evils" are simply situations that displease us in one way or another. We measure our disgust, discomfort, pain, outrage, etc. against ourselves because there is nothing else to measure against. Measuring such things against human preferences quickly reveals that there our measuring sticks are private and cannot be applied to others.
The best we can do is to state, "In our community of belief such things are considered very bad." But if someone belongs to another community of belief they are free to ignore our preferences and if their community is more powerful than ours, we will be wiped out and no evil will have been committed.
Ultimately, whatever is is good. That is consonant with the evolutionary world view which tells us that extinctions are a necessary path to improvements. Though of course improvements are neither good nor bad. They just are.
The atheist has no right to use the word evil. He can only use such terms as dysfunctional, sick, pathological within a given society, undesired, inefficient, reproductively unsound.
Once we conclude there is something in the world that is actively evil, we must inevitably face the other side of that coin: there must be some absolute good which we have measured with. And what can that absolute good be except God?
"It is via such reasoning that I came to be a Christian." --Laszlo Bencze
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