In the story of 'The Lost Sheep', a shepherd has one hundred sheep but has lost one. The lost sheep represents someone who has lost their faith in God, and the shepherd represents Jesus. The other ninety-nine sheep represent all of us.
In my opinion, the wolf represents the Devil guiding the lost sheep to be like him. As the wolf chases the sheep, so does the Devil, trying to tempt him. However, the sheep keeps running away from the wolf, not listening to the Devil, but, the lost sheep gets even more lost.
Before the wolf finally catches the lost sheep, the shepherd saves the lost sheep just in time. This represents that Jesus has found us and saved us from losing our faith in Him.