God expects and deserves honesty. It's in the Bible, Psalm 51:6, TLB. "You deserve honesty from the heart; yes, utter sincerity and truthfulness. Oh give me this wisdom."
Being dishonest about someone is as harmful and lasting as physical wounds. It's in the Bible, Proverbs 25:18, TLB. "Telling lies about someone is as harmful as hitting him with an ax, or wounding him with a sword, or shooting him with a sharp arrow."