Ephesians 4:29 (NASB95)
29 Let no unwholesome word proceed from your mouth, but only such a word as is good for edification according to the need of the moment, so that it will give grace to those who hear.
The Greek word for unwholesome is sapros (σαπρός). It's basic meaning is related to something that is rotting and decaying.
The Greek word for edification is oikodome (οἰκοδομὴν). It carries the meaning of constructing a building. The ESV translates it as 'building up'. This is the process of building each other up in Christ. And we do it not only by our actions but also according to Eph 4:29 by our words.
These two words Paul, by the Holy Spirit, places in contrast to one another in Eph 4:29.
Let no unwholesome word proceed;
But
Only that word which edifies or builds up.
The goal of a Christian's speech is the imparting of GRACE to those who hear (in this case, read). An unwholesome word does not have to be something that is obviously morally reprehensible. Only that word that does not build up, and impart grace to its hearers, that word is unwholesome. The word that brings edification imparts grace.
Colossians 4:6 (NASB95)
6 Let your speech always be with grace, as though seasoned with salt, so that you will know how you should respond to each person.
The NASB translators added 'as though' to help us understand that it is GRACE in our speech that becomes the salt that has seasoned it. A dear friend of mine reminded me of this verse once and asked me what in the Bible was always to be seasoned with salt. In the Old Testament ALL offerings made to God were to be seasoned with salt. When we speak to one another in person or via a forum such as this, our words become offerings.
I want to encourage the brothers and sisters on this forum to let our manner of speech be seasoned with grace to one another and that our offerings be pleasing to God our Father.
Strive for wholesome talk that edifies each other.