What does Matthew 18:13 mean?
Jesus is comparing His Father, God, to a shepherd with 100 sheep. If one of those sheep wandered off away from the flock, the common practice would be for a shepherd to leave the other 99 sheep with another shepherd in order to find the one that had gone astray. Why? Because sheep are valuable, and the shepherd cares for His sheep.Now Jesus continues that when the shepherd finds the missing sheep, he will be truly excited. He will rejoice more over finding the one missing sheep than the 99 that stayed with the flock. That's just human nature. Jesus is showing that it is also the nature of God to rejoice over restoring one of His own "little ones," believers in Jesus, who have gone astray.
What does it mean for a believer in Jesus to go astray? It seems pretty clear that Jesus is talking about believers who give in to temptation and sin. He has warned His disciples with harsh hyperbole in the previous verse just how seriously they should confront their own sinfulness, but He followed that by warning them not to despise any of the other believers in Jesus, even apparently those who fall into sin. His Father is like a shepherd who goes after a missing sheep and brings it home.
God often compared the people of Israel to sheep in the Old Testament. Jesus came to pay the price for our sinfulness and to make it possible for sinful sheep to be forgiven and be given a place with the Father. Isaiah 53:6 puts it this way, "All we like sheep have gone astray; we have turned—every one—to his own way; and the Lord has laid on him the iniquity of us all."