Lewis Beachey preaches on the story of Jehoshaphat in 2 Chronicles 20, highlighting the king's response to a great enemy alliance by seeking the Lord through fasting and prayer. Despite feeling powerless, Jehoshaphat's faith led him to trust in God's promise of victory. The sermon emphasizes the spiritual battle believers face against unseen enemies like spiritual wickedness, urging them to put on the whole armor of God to withstand the devil's schemes.