Jesus has told us to “Go into all the world and preach the gospel to every creature” (Mark 16:15), but he also told us, in the context of preaching the gospel, “Do not give what is sacred to dogs; do not throw your pearls to pigs.” (Matthew 7:6) What did he mean?
The gospel is a thing of great value, and the images used in reference to it reflect this. For instance, it is referred to both as a treasure, and as a beautiful deposit: “We have this treasure in jars of clay…” the Apostle Paul says. (2 Corinthians 4:7) And Timothy is instructed to “Guard the good deposit [the gospel]…” (2 Timothy 1:14) The word “guard” describes the defending of a palace, a place of great importance. Furthermore, Paul says Timothy is equipped to do this “with the help of the Holy Spirit who lives in you.”(2 Timothy 1:14) The value of the gospel is also seen in Jesus’ reference to the kingdom of heaven as a pearl of great worth. (Matthew 13:45-46)
The gospel is to be proclaimed to everyone, but not everyone is interested in the message and some are violently hostile to it. When we meet such hostility we must discontinue evangelising and move on. Certainly this is what the Apostle Paul did on occasion. “On the next Sabbath almost the whole city gathered to hear the word of the Lord. When the Jews saw the crowds, they were filled with jealousy and talked abusively against what Paul was saying… But the Jews incited the God-fearing women of high standing and the leading men of the city. They stirred up persecution against Paul and Barnabas, and expelled them from their region. So they shook the dust from their feet in protest against them and went to Iconium.” (Acts 14:44-51) On another occasion when Paul met with fierce opposition from the Jews, he stopped preaching to them and went to preach the gospel to the Gentiles. “Paul devoted himself exclusively to preaching, testifying to the Jews that Jesus was the Christ. But when the Jews opposed Paul and became abusive, he shook out his clothes in protest and said to them, ‘Your blood be on your own heads! I am clear of my responsibility. From now on I will go to the Gentiles.'” (Acts 18:5-6)
When we continue to preach the saving message of Jesus to hostile people it affords them further opportunity to blaspheme the gospel. It is the equivalent of giving what is sacred to dogs or throwing pearls before pigs, who have absolutely no appreciation of their value. It is not a sign of zeal to preach the gospel to hostile people; rather it is a sign of disobedience to Jesus, who told us to move on and to seek those who appreciate the treasure that is being offered.