Self righteousness is a subjective standard of righteousness. A particular righteousness relative to an individual’s way of living righteously.
It’s a righteousness of the world, which stems from the sinful nature of humanity. And because it’s of the sinful nature of man, it’s man’s attempt to live righteously in his own strength through sinful means. And also, practices righteousness as a self justification.
This kind of righteousness always tends to be proud. Puffed up within self. Loves to judge others as something inferior to it. Not only delights in itself, that it’s not like others, but lords it over those consider to be unrighteous in comparison. There’s a selfish motivation to do good. And without genuine humility, refuses to completely surrender to God.
By no means will God ever accept our righteousness. Our self righteousness is sinful and morally corrupt by nature. Whoever then is arrogantly confident according to their own way, will expose themselves to be unrighteous.
Thus, we need God’s righteousness according to His way by faith in His word. Not our righteousness in accordance to our way by faith in our word. That is making ourselves into a god. And creating our own reality. Defining what is right and wrong. Ultimately idolising self above God.