Breastplate

Breastplate in Scripture refers to two distinct objects: the piece of armor protecting the chest in battle, and the ornate priestly vestment worn by the high priest. The high priest's breastplate (choshen) was a folded square of the same embroidered fabric as the ephod, set with twelve precious stones in four rows of three, each engraved with the name of one of the twelve tribes (Ex. 28:15–30; 39:8–21). Within it were carried the Urim and Thummim, the sacred lots used for discerning God's will. It was called the “breastplate of judgment” and was worn “over his heart” when Aaron entered the sanctuary.

The military breastplate becomes a spiritual metaphor in Isaiah 59:17, where God himself puts on righteousness as a breastplate, and Paul develops this into the full armor of God (Eph. 6:14), identifying the breastplate specifically with righteousness. In 1 Thessalonians 5:8 he describes the breastplate of faith and love, combining Isaian imagery with his characteristic triad of virtues. The protection of the vital organs by a breastplate of moral and spiritual integrity expresses the Pauline conviction that Christian life is a form of warfare requiring active defensive equipment.