I don't think it's possible to blame the Bible's bad rap on mistranslation. The modern translations have the advantage of tremendous research and manpower and are done, by and large, by people with a vested interest in the principles of Christianity. It's not like the translations are done by people looking to give Christianity a black eye.

The Old Testament days were a different time, with completely different value systems. Life was cheap, people were expected to be sheepish followers of their rulers and women were all but property. God was supreme and by today's values God was a despotic, jealous, capricious jerk and there's not much that modern Christians can do about it.

Starting with the Enlightenment of the 1700's, the Christian church lost its stranglehold on western culture. Left more to other forces, the value system drifted away from the traditional values of the Bible (and towards things like democracy). This opened a widening gap of acceptability between the actions of God in the Bible and the actions permitted in our modern world. Just discussing these items could have gotten you burned at the stake in pre-Enlightenment times (another shame for Christianity).

Christianity is faced with a difficult, if not impossible task: to stay true to the values and teachings of a 3000 year-old heritage in the face of modern values (such as individuality, equality for women, avoidance of war, etc). Good luck to them, it's not a task I would envy. It's some help that the New Testament God is kindler and gentler, but the Old Testament is still an albatross around their necks.

Interestingly, Islam has faced the same challenge, but responded by denying modern values. It's yet to be seen if this strategy can work over the long term in an increasingly connected world. Personaly, I think they're in for a world of hurt.