Now the tax collectors and sinners were all drawing near to hear him. And the Pharisees and the scribes murmured, saying, "This man receives sinners and eats with them."
So he told them this parable: "What man of you, having a hundred sheep, if he has lost one of them, does not leave the ninety-nine in the wilderness, and go after the one which is lost, until he finds it? And when he has found it, he lays it on his shoulders, rejoicing. And when he comes home, he calls together his friends and his neighbors, saying to them, 'Rejoice with me, for I have found my sheep which was lost.' Luke 15:1–6 (RSV)
One of the main things that prevent people from seeking to become Christian is Christians. I know it sounds harsh, even judgmental, but it is more accurate than I would admit. Like the Pharisees and scribes, we too quickly see the flaws in others, ruling them out of fellowship. All they could see were sinners who had no place in God's Kingdom.
Jesus knows that the tax collectors and sinners have wandered from God. He knows that they have made a wreck of their lives. He also knows that scolding them for their spiritual state will not turn their hearts to the Father. Nor does He wait for them to come to their senses and come crawling back. He goes after them.
He does not stop seeking until He has found the lost. Once found, He rejoices that He has found 'my sheep,' which was lost. He carries them back to the flock, calling others to join in the rejoicing. He does not forget the sheep was lost, but His joy over their being restored is greater than anger or judgment in His heart.
Can we be so joyless that we cannot celebrate another lost lamb has been restored? We may forget that we have been lost to the Lord, probably more than once in our lives. Each time, He has come looking for us to restore us to His flock. He does this with joy that we are His once more.