I think deism is respectable. A bit unnecessary, perhaps - rather like believing in a Platonic world of forms - but well within the realm of reasonable belief. But theism strikes me as just plain silly. Even supposing that we need to posit a 'Creator' of the universe, why think that a particular ancient religious text has anything accurate to say about Its nature? Why think the Creator would be so petty as to punish those who don't realize that It is real? This is something I touched on in my discussion of why Pascal's Wager is the worst philosophical argument ever. Indeed, I think it provides us with a devastating argument against (most forms of) Christianity:
1) Christianity says that God is benevolent.
2) Christianity says that God would punish an honest disbeliever with eternal damnation.
3) The honest disbeliever is not grievously blameworthy.
4) A benevolent being would not punish someone with eternal damnation if they were not grievously blameworthy.
5) Therefore, Christianity is false.
What say you?