Luke 2:8-20 mentions shepherds keeping watch over their flocks. It's a beautiful story about how God does not judge people by their outward appearance, social status or circumstance, but reveals His love to all who are humble in heart.
Take these shepherds for example. Shepherds were looked down upon by most Jews. First of all, they were dirty and smelled of sheep. They were considered "unclean" by the Pharisees. Shepherds were highly distrusted since most considered them ill-educated and unreliable.
Yet Jesus himself was not hesitant to identify Himself with shepherds, and said, "I am the good shepherd." David, himself in his youth a shepherd, called God by such a title in Psalm 23, saying, "The Lord is my shepherd." We call minsters "pastors," which means shepherd; one who watches over the flock of believers.
These shepherds in Luke have two great distinctions and blessings: 1. They saw and heard the angelic witness to Jesus' birth. They were the first to do so, even before the Magi. 2. They were the first to share and witness of Christ' birth to others. This is important to note since in Jewish civil courts of the time, shepherds were not considered competent enough to give legal testimony.
In this story, Luke gives us a first glimpse into the future ministry of Jesus in which he would use and bless "sinners" in his ministry. God blesses and uses us, not on the basis of our social class standing, but by His unconditional love and mercy. This is the real good news of Christmas.