Jesus said: “Don’t waste what is holy on people who are unholy. Don’t throw your pearls to pigs! They will trample the pearls, then turn and attack you.” Matthew 7:6 NLT
Pigs here are representative of those who would ridicule, reject, and blaspheme the gospel once it has been given to them. We are not to give the gospel of Jesus Christ to someone, who has no other purpose than to trample it and return to his own evil ways. We identify such people through discernment, as indicated in 1. Corinthians 2:15 NLT: “Those who are spiritual can evaluate all things!”
This does not mean that we refrain from preaching the gospel, but if anyone refuses to welcome you or listen to your message, let him or her go, and as the Bible says; shake the dust from your feet as you leave! (See Matthew 10:14)
The gospel is not for those who mock and trample it, and then turn on you and abuse you!