Paul is here helping us to find the kind of words holy living calls for - namely 'thanksgiving'. The word that is translated here as thanksgiving also means 'gratituful', 'pleasing' or 'conversation marked by the gentle cheerfulness of a grateful heart. Eugene Peterson translates this verse - Though some tongues just love the taste of gossip, Christians have better uses for languge than that. Don't talk dirty or silly. That kind of talk doesn't fit our style.
Thanksgiving is our dialect.
We are the very light of God Summing up what we have covered thus far, Paul is working with this toough crowd of christians in Ephesus who been struggling with how now they are to live their lives since turning to faith in Christ. So Paul has spent a great deal of time addresing certain behaviors that are conduct unbecoming, for a Christian. But teaching believers what they must do and what they must not do as a Christ follower doesn't ensure that they will obey the teaching. Rules don't ensure obedience do they. Just ask any parent of a teenager who has been recently grounded.