Criticism
Criticism can be destructive. It's in the Bible, Galatians 5:15, NIV. "If you keep on biting and devouring each other, watch out or you will be destroyed by each other."
Criticism of others often covers the need for self-criticism. It's in the Bible, Matthew 7:1-5, TLB. "Don't criticize, and then you won't be criticized. For others will treat you as you treat them. And why worry about a speck in the eye of a brother when you have a board in your own? Should you say, 'Friend, let me help you get that speck out of your eye,' when you can't even see because of the board in your own? Hypocrite! First get rid of the board. Then you can see to help your brother."
Willingness to forgive is a part of constructive criticism. It's in the Bible, Luke 17:3, NIV. "So watch yourselves. If your brother sins, rebuke him, and if he repents, forgive him."
Those who give it—get it. It's in the Bible, Luke 6:37-38, TLB. "Never criticize or condemn—or it will all come back on you. Go easy on others; then they will do the same for you. For if you give, you will get!"
Christians will wisely learn from valid constructive criticism. It's in the Bible, Proverbs 9:8-9, TLB. "If you rebuke a mocker, you will only get a smart retort; yes, he will snarl at you. So don't bother with him; he will only hate you for trying to help him. But a wise man, when rebuked, will love you all the more. Teach a wise man, and he will be wiser; teach a good man, and he will learn more."
The best protection against criticism is a clear conscience. It's in the Bible, I Peter 3:16, NIV. "Keeping a clear conscience, so that those who speak maliciously against your good behavior in Christ may be ashamed of their slander."