When God gets ready to deal with somebody, He deals with their mouth first.
I love watching my kids interact with each other. They can bicker with each other so quickly, but let another child come into the mix and speak ugly to one of them and they will quickly take up for each other. It's like that old saying, 'You better not talk bad about my sister, but it's ok if I do!' When I hear them arguing about something, I find myself telling them to "hush!" Some days, I feel like that's all I do is go around saying, "hush, hush, hush!"
One time I was talking about somebody and the Lord spoke to me and said, "Well, who do you think you are?" Romans 2:1 says, "Therefore you have no excuse or defense or justification, O man, whoever you are who judges and condems another. For in posing as judge and passing sentence on another, you condemn yourself, because you who judge are habitually practicing the very same things." Gossip, slander, and backbiting all have a root, just like a tree or a flower. The root of these things is judgement and the root of judgement is pride. So when we talk about other people and negatively, it is because we think we are better than they are.
In God's eyes, sin is sin and wrong is wrong. All if it is equally disappointing and distasteful to Him and it is also very dangerous. Jesus warned in Matthew 7:1-2, "Do not judge and criticize and condemn others, so that you may not be judged and criticized and condemned yourselves. For just as you judge and criticize and condemn others, you will be judged and criticized and condemned, and in accordance with the measure you deal out to others, it will be dealt out again to you." When the Lord convicted me of what I had said about another person, He was also saying "That's my child you're talking about!"
So if we have reverential and worshipful fear of the Lord, and if we stand in awe of His name, we should not use our mouths to speak evil against His people. Is God telling you and me to "just hush" when it comes to speaking about other people?