To understand what God means when he speaks about "having put on the breastplate of righteousness," we must understand what a breastplate was in those days, and what is the righteousness of which he speaks. 

There were two kinds of breastplates in biblical times. One was what a soldier wore in battle, and the other one was what a priest wore when he ministered before God in the tabernacle. 

The soldier's was made of small metal links or plates hitched together. This protected his whole upper torso. Goliath wore one of bronze (I Samuel 17:5). 

Then there was one that the high priest wore when he went into the tabernacle once a year to make an atonement for the sins of God's people. It was called the breastplate of judgment. 

This was a richly embroidered ten inch square of linen on which four rows of precious stones (diamond, emerald, sapphire, etc.) were set in gold, with the names of the twelve tribes of Israel engraved on them (Ex. 28:15-21). The high priest was to bind this breastplate on himself with braided golden chains and rings. God said he was to bear the names of the sons of Israel on the breastplate of judgment over his heart when he went into the holy place as a memorial before the Lord continually (Ex. 28:29). 

So also, our Lord, as our High Priest went into the Most Holy Place, to bear the judgment of His people, not with blood of goats and calves, but with His own blood to obtain eternal redemption for us, once for all (Hebrews 9:11-12). 

He carried the names of all His people on His heart, praying for them, sacrificing Himself for them, because they, themselves, are HIS JEWELS, HIS SPECIAL TREASURE. He has made them for Himself (Mal. 3:17). They are so precious to Him that He will give men and people for their life (Isa. 43:4). 

Though Aaron's breastplate was a beautiful piece of work, the Lord's breastplate was much more glorious than Aaron's ever could be. Never again will there be seen one like it on earth. His breastplate was, and is, the righteousness of God. The name written on this breastplate is not just that of a man or a tribe. It is the name of the eternal God -- Jehovah - Tsidkenu -- THE LORD OUR RIGHTEOUSNESS (Jer. 23:5-6). 

This is the breastplate of righteousness that we must put on. It not only imputes His righteousness to us so that we are justified from all our sin by faith in Him, but it is a righteousness worked within us by His Spirit, causing us to be more and more conformed to His image (Rom. 8:11-14, II Cor. 3:17-18). If we don't wear this breastplate, we shall surely perish. Nothing else can bear the holy wrath and vengeance of a holy God against the sin in us. 

May we not stumble over this "Rock" as the Jews did, and continue to go about trying to establish our own righteousness. Jesus Christ is the end of the law for righteousness to everyone who believes. Thanks be to God; He has made us accepted in the Beloved (Rom. 10:3-4, Eph. 1:6). 

Let us, now, put on the breastplate of faith and love, trusting in the Lord for all things. We shall never be struck with a deathblow by any enemy, if we do (I Th. 5:8).