Colossians 4:6 addresses the way we talk, saying that our speech should always be gracious, seasoned with salt (4:6). In the ancient world, salt was valuable, and served at least two purposes as nothing else could do. First it was a purifying agent. In those centuries before refrigeration, salt was used to keep meat fresh beyond a few hours or days. The salt would penetrate the flesh and prevent decay. Salt was also used then for helping wounds to heal.
In the same way, our words are to be redemptive, building people up instead of tearing them down. Beyond that, they should be pure words. It disturbe me when I hear Christians use the same words as Eddie Murphy does in and R-rated movie. Talking like that does absolutely nothing to promote the gospel. In fact, that kind of worldly living hinders the gospel.