In defense of the Bible - it's definitely true that the God of the Old Testament is sometimes portrayed as a petulant jealous deity. Sometimes writers of the OT - such as in the Psalms - make horrific requests of God in their anger. But there are many accounts that show, even in the OT that he is very very patient, and willing to welcome those who change.
I always liked the story of Jonah, who is sent to warn Nineveh of God's wrath. He doesn't go - *mainly* because, he doesn't want them to be warned. He wants them to fry. You know the belly of the whale part, but when he finally reaches Nineveh, he does what he's told - he gives a one sentence sermon, warning them in forty days, wham! they all get it. Then he climbed a hill to watch the fireworks. But the Ninevites got the message, and they changed - and were spared. Meanwhile, Jonah is throwing a fit, because he REALLY wanted to see them "get it". He gets upset because a vine he was resting in the shade of, God withers up, and God asks Jonah, why is he upset over a vine, but not over the 125,000 people of Nineveh?
Some of the butchery elsewhere can seem out of context. For example, you'd see cases where a prophet would tear down pagan altars to gods like Moloch, and kill all its priests. But traditional worship of Moloch involved massive sacrifice of infants - somehow, I have to say they got what they deserved.
In many ways, it seems to me that the God of the OT is written in such a way to describe a powerful but just God who IS merciful and understanding, but nevertheless, just. Today, if a judge let every person off easy, we'd throw him out of office as a pushover. A good judge has to make hard decisions.
The New Testament tends to describe this judge kind of God as something further, more personal - as a father. God is NOT addressed as a father in the OT, but as a sovereign, a king. There's a difference.
Anyway, didn't intend to go on for so long.