Matthew 7:6 is an analogy Jesus used to show how people who have not had their minds opened by God to receive spiritual understanding will often react when they hear the true Gospel.
“Give not that which is holy unto the dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.”
Put another way, Jesus was teaching His disciples not to try to convert those who are not yet being called (John 6:44). Such people are likely to respond by treating God’s truth like dirt.
Just as a pig would trample fine pearls into the mud because it doesn’t know any better and cannot appreciate such worth, the person whose mind is not yet receptive cannot grasp the awesome value of the truth. To them, the truth would be meaningless and would be discarded. They would just trample it underfoot, so to speak.
God’s truth should never be forced upon anyone, but true Christians should “be ready always to give an answer to every man that asketh … a reason of the hope that is in [us], with meekness and fear [gentleness and respect]” (I Pet. 3:15).
In other words, it is right to explain what he believes when someone sincerely asks. Such interest may indicate that God is opening the person’s mind.
Notice how, at another time, Jesus used pearls to express the value of the truth and of God’s Kingdom. He said, “The kingdom of heaven is like unto a merchant man, seeking goodly pearls: Who, when he had found one pearl of great price, went and sold all that he had, and bought it” (Matt. 13:45-46). God wants us to treat His truth like a priceless gem.
The Apple Of God's Eye 