What does the one lost sheep in the parable represent?
The one lost sheep represents the small remnant of Jews who recognized their lost condition, followed the Lord, and became believers that He was the Christ. By contrast, the ninety-nine symbolize the self-righteous Pharisees, Sadducees, and majority of Jews who were lost but did not know it.
Les explains that the parable must be kept within Israel and Jewish custom, not translated into church language. The ninety and nine are the Pharisees, Sadducees, and the majority of Jews. They were without a shepherd but did not know it because they were self-righteous and self-content, like sheep wandering from clump to clump, thinking they were alright while desperately lost. The one sheep, however, knew he was lost, and the shepherd went and saved him. That one sheep represents the little small remnant of Jews who realized they needed the true shepherd, followed the Lord, and became believers that He was the Christ. They let it be known, while the vast majority of Pharisees and religious Jews went on their merry way, not knowing they were lost.