"Do not let any unwholesome talk come out of your mouths." (4:29)As we read on we are encouraged to build others up by giving them helpful words that will be a benefit.
A few verses later Paul writes:
"Nor should there be obscenity, foolish talk or coarse joking, which are out of place." (5:4)Destructive, obscene, vulgar, slanderous and contemptuous speech is forbidden because it is not the nature of God, and thus, not the nature of the people recreated in his image.
But, no where are we forbidden to use "strong language". The apostles, Jesus and the Word of God itself use strong language. Our challenge, if we are to follow suit, is to know what we are talking about and what we are saying. The power of strong language is the Truth that it communicates. Language is not "strong" just because it is loud, or shocking, or makes people feel uncomfortable. Strong language contains and communicates Truth. Indeed, in our culture it may need to be loud and it will most likely shock the hearers and make them uncomfortable. Remember, just because language is shocking and uncomfortable doesn't mean it is unwholesome, obscene, vulgar or inappropriate.
Speak the Truth with Wisdom!