"If Luther’s interpretation is correct, the eighth commandment is an epistemic principle: it has to do with figuring out when we have found the truth about our neighbor. When it comes to the assessment of our neighbor’s words and deeds, we should ‘find ways of excusing him, speak well of him and make the best of everything’ – or as it is often rendered, ‘put the best construction on everything (Small Catechism I.16). This is not just a rule of etiquette. We cannot keep this commandment by first discovering what we suppose to be the hard truth about another’s words and deeds, and then politely keeping quiet about, or softening up the rough edges. The commandment not to bear false witness surely cannot be an injunction to dissemble. Rather, obedience to this commandment has to enter into our very effort to discern the truth about our neighbor in the first place; we cannot suppose that we have got the truth about our neighbor’s words and deeds until we are sure we have put the best possible construction on them. In just this sense, presumably, the apostle Paul enjoins us to speak the truth in love, and warns against ‘evil talk,’ namely that which fails to build up and give grace to those who hear (Ephesians 4:15, 29). If we sense a conflict between what we want to say about our neighbor and that kindness and tenderness of heart without which we grieve the Holy Spirit (Ephesians 4:30, 32) we have a sure sign that we have so far failed to find the truth, and have fastened onto falsehoods of our own invention."
-- Bruce Marshall, quoted by Eugene Rogers in Sexuality and the Christian Body, p. 33