This is one of the reasons I had trouble with Christianity. For instance, "lying lips are an abomination," is in Proverbs. Although it's important to me to tell the truth in most instances, I can think of a few instances where telling a lie certainly wouldn't be morally wrong. Also, "turn the other cheek." I think it's important not to provoke violence but sometimes standing up for yourself is useful and solves the problem.
Also, just a note about slavery. The Christians I know don't have a problem with the verses about slavery in the Bible because of the context. They say slavery, in those days, was a limited-term thing. People would get into financial trouble and sell themselves into slavery to pay back their debts. So it was more like an indentured servant type of thing, for a few years, that was part of the culture at the time.
Also, just a note about slavery. The Christians I know don't have a problem with the verses about slavery in the Bible because of the context. They say slavery, in those days, was a limited-term thing. People would get into financial trouble and sell themselves into slavery to pay back their debts. So it was more like an indentured servant type of thing, for a few years, that was part of the culture at the time.