[1] Then drew near unto him all the publicans and sinners for to hear him. [2] And the Pharisees and scribes murmured, saying, This man receiveth sinners, and eateth with them. [3] And he spake this parable unto them, saying, [4] What man of you, having an hundred sheep, if he lose one of them, doth not leave the ninety and nine in the wilderness, and go after that which is lost, until he find it? [5] And when he hath found it, he layeth it on his shoulders, rejoicing. [6] And when he cometh home, he calleth together his friends and neighbours, saying unto them, Rejoice with me; for I have found my sheep which was lost. [7] I say unto you, that likewise joy shall be in heaven over one sinner that repenteth, more than over ninety and nine just persons, which need no repentance. **

The Pharisees did not want to “associate” with “sinners,” while Jesus not only “received” them but ate with them. Through the means of a parable, Jesus shows them and us spiritual truth. On the surface the subject is “eating” and “receiving sinners,” so we would expect that the parable instead of talking about physical sheep being physically lost in a physical wilderness, is really talking about spiritual sheep being spiritually lost in a spiritual wilderness. Lets see if the Bible agrees with this.
Sheep – Jeremiah. 50:6 My people hath been lost sheep. Lost – Psalm 119:176 I have gone astray like a lost sheep. Proverbs 28:10 Whoso causeth the righteous to go astray in an evil way. Wilderness – Exodus 16:1 the children of Israel came into the Wilderness of Sin. Eat – Jeremiah 15:16 thy words were found and I did eat them.
So now we know from the Bible that spiritual sheep = people; spiritually lost = to be a sinner (gone astray); spiritual wilderness = a sinful place (this world); spiritual eating = studying the words of the Bible. So in this parable, Jesus is saying: if a man (spiritual shepherd) has a hundred people (spiritual sheep) in his care and one person (spiritual sheep) leaves him, the man (spiritual shepherd) will leave the 99 people (spiritual sheep) in his group and go after the one person (spiritual sheep) who is spiritually “lost” in the “wilderness of sin”, and bring him back to himself and his group. In this parable all the sheep were in the “wilderness”, but only one was “lost”. Thus all the people in the shepherd’s group were in a sinful place, but only one was willfully sinning. The other ninety nine just persons which needed no repentance were sinners who had already repented of their sins and been justified by the blood of Jesus.
²³For all have sinned, and come short of the glory of God; ²⁴Being justified freely by his grace through the redemption that is in Christ Jesus: ²⁵Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God; ²⁶To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus
This parable has a double application. The primary meaning is that Jesus is the “Good Shepherd” who has many “spiritual sheep” or people in His care, who love and serve Him and have been “justified” by His blood and His righteous life (just persons). But, there are those who have left Jesus and have “gone astray” in the “wilderness of sin” of this world. They are lost people (lost sheep) who do not know how to return to Jesus (the Good Shepherd), but Jesus Himself will seek for them until He “finds them”. If they will repent, He will justify them by His Blood and carry them safely “home” to heaven. The second application applies to the “undershepherds” or ministers, teachers and lay persons. The “Good Shepherd”, Jesus, left the ninety nine “just persons” and went after the one “lost person”. This is to teach the “Pharisees and Scribes” or church leaders that it is not the righteous or just persons that they are to minister to, but they are to “seek the lost”. The sheep in the “fold” (99) are already “safe in the arms of Jesus.” The parable mentions Jesus “eating” with sinners. This means that Jesus shared spiritual food or the words of Scripture with sinners, or in other words, Jesus gave them Bible Studies. We are to follow His example.