First, bearing a false witness against another is sinful against the truthfulness of God. God is the God of truth – “Now this is eternal life: that they know you, the only true God, and Jesus Christ, whom you have sent” (John 17:3). God’s words are true – “Your righteousness is everlasting and your law is true. … Yet you are near, Lord, and all your commands are true” (Ps 119:142, 151). God hates those who lie – “16 There are six things the Lord hates, seven that are detestable to him: 17 haughty eyes, a lying tongue, hands that shed innocent blood, 18 a heart that devises wicked schemes, feet that are quick to rush into evil, 19 a false witness who pours out lies and a person who stirs up conflict in the community” (Prov 6:16-19). Bearing a false witness is forbidden because it is a direct violation against the honesty of God.
Second, bearing a false witness against another is sinful because a person’s name is valuable. Solomon says, “A good name is more desirable than great riches; to be esteemed is better than silver or gold. Rich and poor have this in common: the Lord is the Maker of them all” (Prov 22:1-2). And when truth is replaced by a lie in a relationship, that relationship is no longer valuable.
Third, bearing a false witness against another is sinful because words matter. Solomon wrote, “Death and life are in the power of the tongue, and those who love it will eat its fruits” (Prov 18:21). The 9th commandment addresses the tongue. This is important because language, in some ways, forms the basis of the human community. And when words cannot be trusted the very fabric of the community will deteriorate.
Fourth, bearing a false witness against another is sinful, because God’s truth is not for sale. Proverbs 23:23 tells us, “Buy truth, and do not sell it; buy wisdom, instruction, and understanding.” Truth is valuable – “the truth, the whole truth and nothing but the truth.” Charles Spurgeon once preached, “Buy the truth. Here is the treasure. … Here is the piece of merchandise which you must buy, but must not sell. You may give all for it, but you may take nothing in exchange for it, since there is nothing that can be likened unto it.”
Fifth, and finally, bearing a false witness against another is sinful because that is how unbelievers speak. To be a liar is to behave like someone who doesn’t know Christ. Paul wrote, “Do not lie to each other, since you have taken off your old self with its practices” (Col 3:9).
Bearing false witness is forbidden because it is not God-like behavior, it destroys relationships in and outside the church, and it compromises truth.