Testing is not sadistic. I have to reprimand my child once in a while, and I don't enjoy doing it. Sometimes, I let her climb something that I know she will fall off from, just so she has the opportunity to learn. Laissez-faire is not sadism, it's necessary to let children become adults. When she doesn't get something that she wants, she's so sad it's like the end of the world (she's 2.5 yrs old, btw). I can totally see a benevolent God up there, letting all the bad stuff happen down here, because what we think is the end of the world or really really bad is merely a bump in the head in the grand scheme of things.
Yeah, in a different world, one where suffering is limited and mostly self inflicted, this would be a strong argument.
In this world, however, were people are born with crippling, ultimately fatal genetic diseases, where there are parasites that live in children's eyes and all sorts of stuff that seems designed to cause as much random, irreversable suffering as possible...
Random? No, because you said sadistic, I was reminded of the book of Job*. Job is tortured by God (or the devil with God's consent but whatever), but it's actually a test that he passes. You could take it literal and say the God is a gambling sadistic SOB, or conclude from it that bad stuff doesn't just happen, your faith is tested through perseverance, and even though it does, God still loves you. This can help people enormously when going through bad times.
Yeah, the Job story strikes me as a perfect example of sadism. Not the classic kind you think of... a more subtle, manipulative kind. The kind thatan abusive husband uses, perhaps.