Let me try to come up with a harder one.
Can someone come up with scriptural support for skepticism or atheism?
I think the closest you're gonna get is where the OT mentions the existence of other, real, existant gods or godlike creatures. Hence Judeo/Christianity is not a true monotheism.
1. Pharoah's cleric turned a stick into two snakes. Only gods can create life. Therefore Egypt's gods exist, independent of Yahweh. (I've since had it pointed out that Islam has fixed up this gaping hole by adding a line to the effect that the cleric used prestidigitation. Of course, if the cleric was skilled enough to conjur two snakes like a stage magician, then certainly Moses could have conjured one, and much more easily. Note that conjuring them does fix the "problem" of polytheism, but the story then loses it's punch as a parable of how badass Yahweh is vis-a-vis other gods.)
2. Psalms refers to Yahweh's battles with Behemoth, the great chaos beast, and Leviathan, the great chaos dragon. These are leftovers from stories from proto-Judiasm and earlier, typically formation of the Earth type stories where the up-and-coming nth generation godling finally beats down the opposition (beasts, dragons, titans, all the other gods, whatever) and assumes his place at the top.
So there's at least something to be skeptical about within the Bible itself -- that the standard interpretation of Christianity as monotheistic is technically inaccurate.