Although some cultures have trained domesticated dogs to become expensive family pets which enjoy the run of the house, they are still dogs.  All dogs, whatever their breed and however cute, affectionate or obedient, are derived from the, now extinct, Grey Wolf.  Under the right conditions even home-bred dogs will start to show some wolf-like characteristics, especially when they are very hungry.  But all over the world, most dogs have no human kindness or domestic home: they will eat whatever they can find.

In Jesus' day, the stray dogs did not discriminate: they ate whatever they could find.  Jesus used their behaviour to teach His disciples to be careful with holy things.  Dogs would have no holy thoughts about the spotless sheep and cattle which had been sacrificed in the temple – only meat unfit for sacrifice was given to dogs (Exodus 22:31).  They would hungrily devour the meat with no thought of its holy purpose.  In the same way, worldly people do not appreciate the value of Jesus Christ, the Lamb of God, who had been sacrificed for the sin of the world.  The world has no care for the gospel as long as they can satisfy themselves and think they can manipulate God into giving them what they want (Acts 8:18-23).

Likewise, pigs have no understanding about fine jewellery.  If precious pearls are on the ground, they will be trampled into the ground by the animals.  If you stand in their way they may trample you too.  Ravenous dogs, if they are unable to find any other food will even attack a live human being, as wolves do; they have no respect for life or limb: they simply want to fill their bellies.  It is the way of dogs, pigs and the world - Jesus was treated like that too (Psalm 22:16).  And after Him, they hounded the church, persecuting the apostles - seeking to destroy the holy Body of Christ, the church (Acts 9:1-5). So Jesus advised that the disciples should be wise and alert to the real dangers, whilst presenting Jesus to the world (Philippians 3:18-21).  Meanwhile, false teachers are like dogs who used God’s holy people for their own purposes (Isaiah 56:11; Revelation 22:15)

Jesus, the church, the gospel and the Bible are precious.  Without exposure to them, the world cannot know how to be saved.  But at the same time the world and its evil master hates them and will do whatever is necessary to try to destroy them.  So Christians worldwide, and all servants of the gospel, are treading a tightrope as they share the information which will expose evil and command obedience to Christ.  They must speak about Jesus but always risk persecution.  So, both they and we need to discern which people are hungry for the message, because they value what God has for them, and which want to destroy the message, its messengers and its followers.