"That which is altogether just shalt thou follow, that thou mayest live, and inherit the land which the LORD thy God giveth thee." (Deuteronony 16:20)
Under the Old Covenant, under law, man has to pursue righteousness. We need to get it, acquire it any way we can.
Under grace, God gives us righteousness as as gift, and in fact we are invited to keep receiving that gift (Romans 5:17)
Under law, righteousness is something that you have to attain, that you have to follow.
Under grace, righteousness is something that you become, because Jesus, who is our righteousness, imputes His righteousness to us:
"For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him." (2 Corinthians 5:21)
"Blessed is the man to whom the Lord will not impute sin." (Romans 4:8)
Paul writes beforehand:
"But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness." (Romans 4:5)
This is all too wonderful a revelation not to write about, and it's a very simple, straightforward revelation, too!
I have to write it this way:
Under law, you have to pursue righteousness. Under grace, righteousness pursues you! AMEN!
And that righteousness is a Person! His name is Jesus!
"But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:" (1 Corinthians 1:30)