When we gossip about someone, we're talking about them–and how do we know if what we're saying is absolutely accurate and true? Or how do we know if it's the whole story, or only part of the truth? And how do we know whether or not the person we're talking to will repeat what we say accurately to someone else?
The answer is–we don't! And that's one reason the Bible tells us not to gossip. Gossip, by definition, is saying something about a person behind their back–that is, saying something we wouldn't say to their face. I've always tried to follow this rule in life: Never say something about a person that you wouldn't also say to their face.
Gossiping also is wrong because it hurts the reputation of the person we're talking about. When we tear someone down (even in subtle ways), we are hurting them, and also separating them from their friends. The Bible warns, "A gossip betrays a confidence; so avoid a man who talks too much" (Proverbs 20:19). It also says, "A gossip separates close friends" (Proverbs 16:28).
Face honestly your sin of gossiping, and commit it–and your whole life–to Christ. Then let the Psalmist's prayer become yours: "Set a guard over my mouth, O Lord; keep watch over the door of my lips" (Psalm 141:3).