Skeptical theism is the view that God exists but that we should be skeptical of our ability to discern God’s reasons for acting or refraining from acting in any particular instance. In particular, says the skeptical theist, we should not grant that our inability to think of a good reason for doing or allowing something is indicative of whether or not God might have a good reason for doing or allowing something. If there is a God, he knows much more than we do about the relevant facts, and thus it would not be surprising at all if he has reasons for doing or allowing something that we cannot fathom.
If skeptical theism is true, it appears to undercut the primary argument for atheism, namely the argument from evil. This is because skeptical theism provides a reason to be skeptical of a crucial premise in the argument from evil, namely the premise that asserts that at least some of the evils in our world are gratuitous. If we are not in a position to tell whether God has a reason for allowing any particular instance of evil, then we are not in a position to judge whether any of the evils in our world are gratuitous. And if we cannot tell whether any of the evils in our world are gratuitous, then we cannot appeal to the existence of gratuitous evil to conclude that God does not exist. The remainder of this article explains skeptical theism more fully, applies it to the argument from evil, and surveys the reasons for and against being a skeptical theist. (continue article)
— Justin P. McBrayer at the Internet Encyclopedia of Philosophy