The Bible is great at showing us where we are wrong. That's what it means to rebuke. We all have things in our life that we believe are right, but they are wrong. Things that we think are good, but are bad. Things that we think are true, but are untrue. Just because you are sure of something, that doesn't mean that you are right. The fact that you are an imperfect human means that you can be wrong. God's word, however, is never wrong. The whole Bible is useful for rebuking.