In Mark 9, Jesus said:
Salt is good: but if the salt have lost his saltness, wherewith will ye season it? Have salt in yourselves, and have peace one with another.
(Mark 9:50)
We believers need to remain "salty" in our families, especially with our spouse and children. Many believers have no trouble whatsoever being kind to people—until they get home, and then "threshold metamorphosis" sets in.

The moment their foot steps across the threshold of their home, they change from a kind, loving person into a thoughtless, rude ogre.

For example, families are often in the process of arguing and wounding one another with cruel, hateful words when suddenly the phone rings. One of the family members picks up the receiver and sweetly answers, "Hello? Why yes, he's here. One moment, please."

Then he covers the mouthpiece of the receiver, and rudely yells, "Hey, come answer this thing—it's for you!"

Actions such as these are an indication of a lack of kindness. Believers must realize that when they treat their own spouse or children with less respect and courtesy than they treat others, they are committing sin.

The fruit of kindness enables one to be gentle and sweet to the members of his family in spite of all the little irritations that go with living together day in and day out.

This fruit is needful in light of the fact that, regardless of what the popular songs say, someone does know what goes on "behind closed doors." That someone is God.

Our heavenly Father knows exactly what takes place in individual households of His children, and He deals with them accordingly.

God is very much concerned with how we believers treat our spouse and children. In fact, His is so concerned that He impressed upon the Apostle Paul to write:
But if any provide not for his own, and specially for those of his own house, he hath denied the faith, and is worse than an infidel.
(1 Tim. 5:8)
This issue of family kindness was so important to Paul he dealt with it in at least two other letters:
So ought men to love their wives as their own bodies. He that loveth his wife loveth himself.

For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church.
(Eph. 5:28-29)

...teach the young women to be sober, to love their husbands, to love their children,

To be discreet, chaste, keepers at home, good, obedient to their own husbands, that the word of God be not blasphemed.
(Titus 2:4-5)
The fruit of kindness enables husbands to be kind to their wives no matter how they respond; and the fruit of kindness enables wives to be kind to their husbands regardless of how they act.

The fruit of kindness, therefore, enables husbands and wives to fulfill the Word concerning how they are to treat one another.

Source: A Call For Character by Greg Zoschak
Excerpt permission granted by Harrison House Publishers