Jesus is illustrating the problem with treating holy things as common by using a reference to throwing meat sacrificed to God to animals. In His time, dogs and pigs were considered unclean and dangerous (Psalm 22:16, 59:14, 80:13). He is speaking of people who are set in their sinful ways (Philippians 3:2), degenerating (2 Peter 2:22) and deviant (Revelation 22:15). Today, it would be akin to offering the Lord’s Supper to those who hate Him.
There is a difference between destructive criticism and careful discernment. Jesus was warning us about standing over someone as judge when we haven’t yet looked in the mirror (Matthew 7:1-5). Now He instructs us that even when we have looked in the mirror, we should be careful who we are dealing with, because some people are not believers, they remain profane, and to give them wisdom is to invite their wrath (Proverbs 9:7-8). Don’t be mouthy and think this makes you a martyr for ministry.
Some do not value the vision of God (Proverbs 11:22). They are wise in their own eyes (Proverbs 3:7, 12:15, 26:12 / Isaiah 5:21 / Romans 12:16), they despise doctrine and become incensed against instruction. If you try and give them something of value, they may become violent. Yes we are supposed to try and help people (Galatians 6:10), but we must be prudent. We are to present the gospel, but when people become abusive and blasphemous, it’s time to cease.
It is the same in the church. Admonishing, correcting, and exhorting a believer is the right thing to do (2 Timothy 4:2 / Hebrews 3:13), but sometimes people persist in their perversity, and we are to let them go (Titus 3:10-11). If they are hurting, hungry, and hearing what you have to say, by all means, continue. Yes we should plead with people, but there comes a time when we are not to waste our words on those who won’t listen.