Charles Ellicott Commentary Colossians 4:6

"Let your speech be always with grace, seasoned with salt, that ye may know how ye ought to answer each one." — Colossians 4:6 (ASV)

Seasoned with salt. It seems impossible not to trace here a reference to our Lord's words in Mark 9:50, Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves. There the salt is spoken of as the preservative from corruption, and the warning against “corrupt” words in Ephesians 4:29 has been thought to point in the same direction.

But the context certainly appears to suggest that the use of the salt is to teach “how to answer every man,” and that this answer (like the “reason,” or defence, of 1 Peter 3:15) is to be given to “those without.” Probably, therefore, the “seasoning with salt” is to provide against insipidity (thus, to some extent, in accordance with the classic usage of the word). Their speech is to be primarily “with grace,” kindled by the true life of Christian grace in it; secondarily, however, it is to have good sense and point, so as to be effective for the inquirer or against the scoffer.