It was the Old Testament that first got me thinking, as well. The WT's literal interpretation of the flood story was something I could never fully get behind, even when I was a fully believing JW. And God punishing David for murder and adultery by killing his infant son never sat well with me, either.
It was my doubts about the bible, and God himself, that made me open to researching the JW religion, specifically. Looking back, now, it's hard for me to believe that I was able to swallow any of it for as long as I did.