The sermon emphasizes the necessity of spiritual armor, particularly the shield of faith, to withstand the devil's attacks and the forces of darkness. Drawing from Ephesians 6, the message highlights that true strength comes not from human ability but from relying on God's power and might, urging listeners to actively engage in spiritual warfare by knowing and applying God's promises. The speaker illustrates this through the Roman soldier's shield and the example of unwavering faith demonstrated in the face of tragedy, ultimately calling believers to pick up their shields and trust in God's goodness, even amidst challenging circumstances.