If one remembers the song called "The Spoonful of Sugar", it speaks the truth that it helps the medicine go down and how true it is. Matthew 5:13 has Jesus calling the Christians to be salt and not sugar. The real Gospel of Jesus Christ is salty and not sugary. Speaking of sugar, the great preacher Charles H. Spurgeon said, "God chooses not milksops destitute of backbone to wear His glory upon their faces. We have plenty of men made of sugar nowadays, that melt into the stream of popular opinion but these shall never ascend into the hill of the Lord, nor stand in His holy place, nor wear the tokens of His glory."
When Christians are called to be salt, what does that mean? Salt is used as a preservative as there was a lack of refrigeration back then at the same time, it is a flavor enhancer. Most people do not see the medical value of salt that it's actually some form of disinfectant too. While rubbing salt to the wound really stings but do you know it also disinfects? Do you know certain sodium (salt) compounds are actually mixed into your over the counter medication for wounds, gingivitis and sore throat? Do you know that sea salt are also used for cleaning the external part of the body? While these salt compound containing products may hurt the wound but they also heal the wound at the same time by disinfecting the bacteria and actually closing the wound.
Christians are also called to have their speech seasoned in salt in Colossians 4:6. To have one's speech seasoned with salt does not mean literally seasoning one's mouth in salt before speaking. What it means is this which I quote Dr. John F. MacArthur as he says, "The speech of the new man must also be seasoned… with salt. It is not only to be gracious, but also to have an effect. Salt can sting when rubbed into a wound (cf. Prov. 27:6). It also prevents corruption. Believers' speech should act as a purifying influence, rescuing conversation from the filth that so often engulfs it. Salt also adds flavor, and the speech of the new man should add charm and wit to conversation." That also means no sugar coating. If you love the person too much, you will tell them the salty truth instead of the sweet lie. A sweet lie comforts then kills but the salty truth may give you discomfort for now but it heals for better comfort.