When we're talking about who we are as Christian, our character matters. People look to us to be an example of Christianity, and when we misbehave, we only substantiate a belief that all Christians are hypocritical. We need to allow Christ to build up our character and as we look at the Bible we can see that character matters:
2 Timothy 3:16 -All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness (NIV)