Today’s name for God is “Jehovah-tsidkenu” – “The Lord our Righteousness” (Jeremiah 23:6). It is a distinctly Messianic title. All the way through the Bible we see God as a “Righteous God” and One who demands that we are “holy” too (Leviticus 11:44; 19:2; 20:7; 7:26). And right through the Bible the way we are “justified” (made right with God) is BY FAITH, both in the Old Testament as well as the New Testament.
This name tell us how this happens: God does it! It is something we cannot do for ourselves. We do it BY FAITH – “God becomes our righteousness” The New Testament expresses it exactly: ‘He who knew no sin (Jesus) was “made sin for us……that we might be made the righteousness of God in Him‘ (2Cor 5:21).
Martin Luther called it “THE GREAT EXCHANGE”. We lay our sin on Christ and in exchange take His righteousness for ourselves.