What makes us think God is perfect?

Bookworm posted a discussion of the Episcopal Church’s tacit admission that God isn’t perfect.  That raises the question:  Why should we believe He is?

Assume there is a God.  Personally, I’m skeptical, but assume it.  Assume God created the universe.  This replaces a great mystery (where the universe came from) with an even greater mystery (where God came from), but assume it.  Assume that God is still actively and personally involved in the creation of each of us individually.  I don’t see a lot of evidence of that, but assume it.

If those assumptions are true, then God is a pretty powerful fellow.  But does that make Him perfect?  After all, we are fond of saying that power corrupts and absolute power corrupts absolutely.  God has the ultimate absolute power.  How do we know He has not been ultimately corrupted?  Even if He hasn’t been, how do we know that he never makes mistakes?  Just because He has the power to create a human being, it doesn’t follow that He has the power to create each of them exactly as he wants them.  Returning to the subject of Bookworm’s post, even if He could create every person exactly as He wanted them to be, who is to say He doesn’t want to put men in women’s bodies and women in men’s bodies? Maybe He’s just playing with us.  Maybe He’s just experimenting to see how we’ll react.  After all, it is a basic tenant of Episcopal faith that He creates each of us as an imperfect creature. Maybe this is just another imperfection that He quite intentionally, not mistakenly at all, put into some of us.  Why do we automatically assume this was a mistake?

Anyway, why should we think that God is perfect in His power, or even good in His intentions?  How do we know?  What evidence is there, either way?