I'll give you one example: a lot of people died in Salem at the hands of God-fearing people because of a mistranslation. According to the footnotes in the Bible provided to me by the Church of my youth, the phrase "suffer not a witch to live" is less than correct. According to that Bible, in the footnotes, the more accurate translation of the phrase is "suffer not a poisoner to live."
http://www.hollowhill.com/fun/halloween/witch-bible.htm
This is still in hot dispute, based on what I learned in college courses of comparative religions, so you can't take the link above as gospel. But, in my gut, I believe the quote as originally published is wrong. The second possibility fits better with my perception of Christianity.
Well I don't what bible you are talking about but the word witch or sorceress in Ex 22:18 is an accurate translation. The word in question is the Hebrew "Kasap" and in context in the OT always means someone who practices supernatural powers. See: Deuteronomy 18:10 and 2 Chronicles 33:6. I would also note that less people were killed in the entire Salem incident than are murdered in Chicago on any given weekend. And Salem was an isolated affair, so Biblical communities have a much better track record than post-Christian contemporary America.
Witch burnings happened long before Salem and there was never any Scriptural justification for it. There is no where in Scripture that says burning at the stake is the way to deal with witches, not to mention that that was the OT Law, not the NT message of grace.
People didn't burn witches and others at the stake because of the Bible or religion, but because they were ignorant of it.