This is the third part in an eight-part series on “the armor of God” in Ephesians 6. It starts here.

Stand therefore, having girded your waist with truth, having put on the breastplate of righteousness . . . (Eph. 6:14)

The “breastplate” is the first piece of defensive armor that Paul names. This one and the “helmet of salvation” were both mentioned by Isaiah in a Messianic prophecy:

He saw that there was no man,
And wondered that there was no intercessor;
Therefore His own arm brought salvation for Him;
And His own righteousness, it sustained Him.
For He put on righteousness as a breastplate,
And a helmet of salvation on His head;
He put on the garments of vengeance for clothing,
And was clad with zeal as a cloak.
(Isa. 59:16-17)

Paul also has a similar “breastplate” metaphor in one of his other letters:

But let us who are of the day be sober, putting on the breastplate of faith and love, and as a helmet the hope of salvation. (1 Th. 5:8)

Paul is not afraid to come up with his own metaphors (like “the belt of truth”), but he also couches everything in the wisdom of tradition. When he puts together metaphors, they tend to be metaphors that were already used in Scripture.

The Breastplate of Judgment?

The connection between “righteousness” and the “breastplate” is no mistake. Although the Treasury of Scripture Knowledge doesn’t mention the cross-reference, both Isaiah and Paul would have been well aware of the high priest’s “breastplate of judgment,” first introduced as such in Exodus 28:15. The word “breastplate” is only used in two contexts in the Bible: the priest’s breastplate of judgment, and the metaphorical breastplate of righteousness (or, in 1 Thessalonians, “faith and love”). Although there are different shades of meaning, the two terms (“judgment” and “righteousness”) are too close in meaning to think that either Paul or Isaiah had anything else in mind.

With that in mind, I believe that the breastplate of righteousness refers to righteous decision-making. The meaning of “judgment” in Exodus 28 is not divine punishment; it means something more like “discernment” or “what is right.”

The Urim and Thummim

The priest’s breastplate is a rather mysterious symbol if we take it as connected to divine judgment, in the sense of punishment and reward. But it becomes much clearer when we take judgment to mean “decision-making,” in connection with the Urim and Thummim. These were actually consulted in the Old Testament very seldom: Saul consulted them at least twice while making war against the Philistines (1 Sam. 14:41 & 28:6),  and Ezra desired to consult them on return from exile, but they had apparently been permanently lost (Ezra 2:63, Neh. 7:65).

The Urim and Thummim are rather mysterious in the Old Testament, but we do know that:

• They were a decision-making tool used by the high priest, likely quite similar to flipping a coin.
• Their name is Hebrew for “lights and perfections,” which seems to point to wise decision-making, but doesn’t say anything about their actual use.
• They are not frequently mentioned, and in fact word from a prophet and even dreams are much more frequent in the Old Testament (cf. 1 Sam. 28:6).
• It also appears they fell out of use after David’s time, and were lost by the time of Ezra.
• They are not mentioned in the New Testament.

The Urim and Thummim in the breastplate symbolize for us the simple fact of consulting God when making decisions. But one danger is, this can be over-emphasized, to the point that we paralyze young believers until they have some spiritual experience, proving God approves of their next decision.

Guarding Your Heart

The basic function of a breastplate is to protect the vital organs such as the heart. For that reason, it is common to link the “breastplate of righteousness” in Ephesians to Proverbs 4:23:

Keep thy heart with all diligence; for out of it are the issues of life.

As I have written elsewhere, the “heart” in Scripture represents thoughts and intentions, not just emotions. This makes sense when we reflect that the priest’s breastplate held the Urim and Thummim, the two stones that the priest used to make decisions:

And you shall put in the breastplate of judgment the Urim and the Thummim, and they shall be over Aaron’s heart when he goes in before the LORD. So Aaron shall bear the judgment of the children of Israel over his heart before the LORD continually. (Ex. 28:30)

When the proverb tells us “guard your heart,” I believe it’s talking about protecting your thought-life and your decisions. I have seen people who were walking with God fall into strange cult-like behavior, and I believe one of the main drivers was their desire for spiritual help in decision-making—when we become lost on this point, some will begin to consult forbidden means like fortune-tellers, astrology, or seances. These lead them into spiritual entanglement and doctrinal confusion, and they end up forgetting the righteousness that is found in Christ.

When we believe that righteousness is found in Christ, it enables us to make decisions with confidence, knowing that he is with us and for us, and that he is empowering us and giving us wisdom through his Word and Spirit. The Bible also gives us a firm footing, so that we don’t always have to wait for a special word—we have the Word. There are times when the Holy Spirit will prompt us to wait until it is the right moment or until we understand a situation better before making a decision; in other times, having consulted the firm foundation of God’s Word, walking in the wisdom of Christian history, and staying in close contact with trustworthy Christian brothers and sisters, we can take bold steps, especially when God’s honor is at stake.