In a few months I'm giving a seminar on the above title.
Where to begin? First thing that occurs to me is that, in my experience, we Christians often do both - maybe we swear in our own language and we gossip with good motives, but nonetheless we do do them. We are warned about our speech - not to slander, or indulge in coarse talk or to bit and devour... but why? Why is that out of step with gospel living? How would you approach this subject? How can I give a gospel-grace motivated answer?
Answers on a postcard, or at least in comments... please!