Mike Bickle discusses the anointing of David in Bethlehem as a pivotal moment in God's plan, following the rejection of Saul. He emphasizes that God's choice of David, a seemingly unqualified teenager, illustrates that God values the heart over outward appearances. Bickle highlights the importance of understanding one's calling as being for God and for the benefit of others, rather than for personal gain. He also notes that God's timing is often slow, requiring patience and faithfulness, as David would wait many years before becoming king. Ultimately, the sermon encourages believers to recognize their worth in God's eyes and to serve diligently, regardless of their current status or recognition.