1John 1:9 meaning, under his blood, our righteousness

Through His Blood
Our Righteousness

1John 1:9
If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.(KJV)

"Just" and un-"righteousness" is from the Greek adjective dikaios, meaning keeping or matching up perfectly with the word of God and therefore innocent, faultless and guiltless in God's eyes. On the other hand, self righteousness is being faultless in one's own eyes.

Without Christ
God's word says that the heart of man is desperately wicked (Jer.17:9). Its righteousness is as filthy rags (Rom.3:10-12). If we say we are righteous, or at least "not so bad", it is based on self deception (1Jn.1:8) and taking a position opposite what God has said (1Jn.1:10).

With Christ
God's word did not stop at the revelation of my wretched condition, He also gave good news (Rom.3:21-22), that all who come to him with a heart broken of sin, He will wash and heal (Matt.9:12-13, 1Tim.1:15). All of us incessantly fall short of God's word (Rom.7:7-8), but in Christ God is faithful to do exactly what he promised (Jn.6:37,40); washing away our sins (Is.1:18) and wrapping us in the righteousness of Christ (2Cor.5:21).

From the day am saved until the day I am received into heaven, I cannot add one whit of righteousness to that which enfolds me the moment I am born in Christ (Rom.10:4, Phil.3:9). The righteousness of Christ in me can and should be magnified as I trust and obey, but there is no adding to it (Phi1:10-11, 20, 2:12-13).

You are of purer eyes than to behold evil, And cannot look on wickedness... (Hab.1:13)