I make no bones about the fact that I despise the Old Testament. It is a wretched book, filled with fanciful depictions of the actions and decrees of one particularly nasty mid-Eastern deity, Yahweh. If you want to demonstrate the inhumanity of Judaism, you will find fertile fields to reap in those books. But that is not the worst the Bible has to offer, by far. You would have to go to the New Testament for that gem: Hell.
In the Old Testament, God spent a lot of time killing and demanding that his followers kill, whether it be women and children(see the book of Joshua for a sampling) or blasphemous Israelites doing such atrocious deeds as picking up sticks and offering incense. He railed about how he would bring destruction upon his enemies heads. He threatened to pursue vengeance against men, even unto their offspring for generations. But it took Jesus to come up with the coup de gras: eternal torment.
In every way it is possible to look at the issue, the idea of Hell is a injustice. It lasts for eternity. It is, literally, an infinite punishment. To be just, a punishment should fit the crime that inspired it. As finite beings, we cannot commit such a crime. Furthermore, the Bible tells us repeatedly that we don't have an understanding of the full picture. So, Hell is an infinite punishment for finite crimes committed by finite beings who have only a finite understanding of an infinite moral situation.
Yahweh only threatened death and mayhem. Jesus wants to keep killing you forever.