By broad definition, is not theism the belief in one God as the creator and ruler of the universe, without rejection of revelation? In my personal opinion, many who believe in God as our creator also believe in a God of mercy. How is it that a God "who doesn't cut down evil people" become an argument against theism?
The philosophical conception of God is that of a being that is perfect in terms of knowledge (omniscience), power (omnipotence), and goodness (omnibenevolence) (see, e.g., http://www.iep.utm.edu/god-west/). Now, if the fact that sometimes good people suffer while evil people flourish is an evil, then this fact presents a sort of problem of evil for theism (see, e.g., http://plato.stanford.edu/entries/evil/). The problem is how could God--who is supposed to be omnipotent, omniscient, and morally perfect--allow for this evil to occur?
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