Luke 15:7 (NKJV)
I say to you that likewise there will be more joy in heaven over one sinner who repents than over ninety-nine just persons who need no repentance.
The parable of the Lost Sheep shows how God will go after even one who is lost. Perhaps you have heard it said that if you were the only one on earth, Jesus would have died just for you. I used to wonder if that were really true but this parable puts away any doubt about that. Look at how heaven rejoices over the salvation of a single person!
By the way, lest you think you may be one of the ninety-nine who need no repentance, see the following verses:
Isaiah 53:6 (NKJV)
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.
Romans 3:10-12 (NKJV)
As it is written: "There is none righteous, no, not one; There is none who understands; There is none who seeks after God. They have all turned aside; They have together become unprofitable; There is none who does good, no, not one."