What is the significance of the shield of faith?

from the old testament

• In Ephesians 6, several of Paul’s pieces of armor came from the Old Testament, specifically Isaiah 59:17, which describes the Messiah: “He put on righteousness as a breastplate, and a helmet of salvation on his head; he put on garments of vengeance for clothing, and wrapped himself in zeal as a cloak.” It’s thus plausible that Paul was drawing on some Old Testament imagery for the shield, though there’s no direct reference.
• For example, God is often described as “a shield for all those who take refuge in him” (2 Samuel 22:31; cf. Genesis 15:1; Psalm 18:2). Taking refuge in God means trusting in His strength to get through a situation. Like a shield, God protects His people from a disastrous end. Note: It’s not a reference to guaranteed safety, but a promise that God is always faithful to His people: “He will cover you with his pinions, and under his wings you will find refuge; his faithfulness is a shield and buckler” (Psalm 91:4). God protects through difficulties, not by removing them.

from the new testament

• For the believer, difficulties come from every side. In Ephesians 6:10–20, Paul focuses on attacks from spiritual forces (Ephesians 6:12) and, specifically, “the schemes of the devil” (Ephesians 6:11). He describes various aspects of a believer’s spiritual life as different pieces of armor.
• Near the end of the list, in Ephesians 6:16, Paul says, “In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one.” The phrase translated as “in all circumstances” in the ESV is translated as “in addition to all” in other translations, such as the NASB. However, the ESV more helpfully clarifies that faith is a shield that is always there, rather than simply another piece of armor. Just as Paul later says that the armor is worn by “praying at all times” (Ephesians 6:18), one’s faith is to be covering at all times. Note: The KJV wrongly translates this as “above all,” based on a manuscript error. However, faith is not the most important thing (above all), but the aspect that permeates all other spiritual practices.
• By “faith,” he is likely referring both to salvation and one’s assurance of faith. Throughout Ephesians, he has been discussing both, so both are probable here. For example, he referred to his readers as you who “heard the word of truth, the gospel of your salvation, and believed in him” (Ephesians 1:13). He reminded them that “by grace you have been saved through faith. And this is not your own doing; it is the gift of God, 9 not a result of works, so that no one may boast” (Ephesians 2:8–9). He also noted that believers have “boldness and access with confidence through our faith in him” (Ephesians 3:12).
• Paul describes this covering as the “shield of faith.” As noted in the Old Testament section, Paul may be alluding to God as a shield, since other parts of the armor also reference Old Testament ideas. However, because it’s less of a direct quote, many scholars believe Paul is simply using the imagery of a Roman soldier’s shield. Such a shield was large enough for a soldier to crouch behind to protect themselves from a barrage of arrows. Given that Paul does reference a barrage of Satan’s darts (arrows), it is likely the imagery he expected his readers to understand.
• He doesn’t describe what those “arrows” represent, but as “schemes of the devil” (Ephesians 6:11), they most naturally refer to temptations (1 Corinthians 10:13) and lies (John 8:44) that he uses to try to knock a believer off his or her feet. They may also refer to the accusations he lodges against believers before God (Revelation 12:10).
• The strength of faith is not the strength of one’s belief, but one’s object of faith, namely Jesus. When one remembers that salvation is through Him alone (John 14:6), not one’s works (Ephesians 2:8–9), and that He loses none He saves (John 6:39), and that He will resurrect His people in the end (John 6:40), then Satan’s arrows lose much of their effectiveness.

implications for today

Satan pulls no punches and will do or say anything—anything—to bring believers down. But they have one key defensive piece of armor: faith. This is because faith isn’t just the entry into salvation; it’s the ground of a believer’s assurance. By remembering that salvation has been, is, and always will be based on Jesus’ work on the cross (Hebrews 10:10–14) and God’s gracious application of it to the believer (Ephesians 2:8–9), there is nothing Satan can do to remove a believer from God’s hands.

Faith is therefore the shield we put up when Satan reminds us we aren’t good enough to be saved. We aren’t, but Jesus is, and it’s His righteousness that saves us (2 Corinthians 5:21). Faith is the shield we put up when we sin, and Satan tells us God hates us now. It reminds us that God has set His eternal love on us through Jesus (Romans 8:38–39), who will never let us go (John 10:27–29). Faith is the shield when life is hard and things are going badly, and Satan says, “See—that proves God doesn’t love you,” because it reminds us that God disciplines those He loves (Hebrews 12:6) and uses suffering to strengthen us against Satan’s attacks (James 1:2–4; 1 Peter 5:9–10).

Believer: hide behind that shield. Don’t attempt to fight off Satan’s arrows on your own. You can’t beat him at his game. But Christ has already defeated him. Crouch down, put up your shield, and remind yourself of what He has done!