Our tongue is a God given gift, and as Christian we must use it wisely. In the Bible there are many texts that illustrate how we should speak with our tongues, and how we shouldn't speak with it.
God has given man a tongue to speak with, but we have abused the gift of speech. It is clear in the Bible that God's hates cursing and deceit that is found in man's mouth. God will not let the man who curses with his tongue go unpunished. David wrote in Psalms 12:3 "God will cut of all flattering lips, and the tongue that speaketh proud things." The sinners tongue will be punished with fire from hell, so that on the Day of Judgment they will no longer deny that Jesus is Christ. It says in Philippians 2:11 says "and that every tongue shall confess that Jesus Christ is Lord, to the glory of God the Father.".
Words express ideas and reveal what is in our heart. Therefore, words cause troubles. Jesus said, "0 generation of vipers, how can ye being evil speak good things? For out of the abundance of the heart the mouth speaketh." (Matthew 12:34) James says that the man who is able to control a tongue of fire is a perfect man and able to bridle the whole body. Our heart and tongue are connected; what is in our heart is what comes out of our mouths. If we don't have anything nice to say, then we ought to bridle our tongues by saying nothing.
As Christians we are to live separate from this world; we can not only do that by our actions but also how we speak to each other. We are to have a tongue that speaks kind things to one another. But most of all God has given us a tongue so we speak and sing of the mercies and loving-kindness of the Lord. We can also witness of all the great things the LORD has .