What does Ephesians 6:16 mean?

One of an ancient soldier's most important tools was a shield. It was essential to protect against enemy attacks, whether swords, arrows, stones, spears, or other attacks. This was such a powerful implement that shields are often associated with strength in the Old Testament. God calls Himself a shield to Abraham (Genesis 15:1) and served as a shield to Israel (Deuteronomy 33:29). Used in formations, cooperating with other soldiers, shields were the defining equipment in many battles.

Faith, in this case, is what deflects the attacks of the enemy. The other parts of the armor will protect the soldier if the shield is bypassed. But the strongest defense is the shield: it actually protects the rest of the armor! Note, though, that the analogy of a "shield of faith" also counters the frequent criticism of religion as "blind faith." Shields are purposeful instruments, not walls to hide behind. Shields, by their nature, are meant to be used with strategy, awareness, and cooperation.

The beauty of a Roman shield was its ability to resist nearly any type of attack. In this context, Paul notes that the shield of faith "can extinguish all the flaming darts of the evil one." The attack he mentions is fiery arrows, a common tactic in ancient war. Even a Roman breastplate could be pierced by an arrow. Shields prone to catch fire were vulnerable. Roman shields were lined with leather, and usually soaked with water before a battle. In other words, the One providing the armor gives His troops equipment perfectly suited to surviving the enemy onslaught.

Also notice the attack is from the "evil one," Satan. Elsewhere, Jesus teaches to pray for protection against Satan as the evil one (Matthew 6:13). Satan cannot be everywhere at once since he is not God, yet Paul seems to indicate Satan attempts to attack every believer he can. Like a military commander, he can attack Christians indirectly through his demons.

Interestingly, the shield is the only defensive piece of armor which can also protect other people. Ancient soldiers would typically fight in formation, interlocking their shields. This meant each man protected both himself, and others, with his shield. In the community of believers, cooperation, unity, and holiness are crucial. When we work "in formation," we form a wall of faith which makes the entire church safer and stronger.