Righteousness is a gift from God received by grace only, through faith only, in Christ only. Righteousness becomes ours through two means – 𝗷𝘂𝘀𝘁𝗶𝗳𝗶𝗰𝗮𝘁𝗶𝗼𝗻 and 𝘀𝗮𝗻𝗰𝘁𝗶𝗳𝗶𝗰𝗮𝘁𝗶𝗼𝗻 – the former an 𝗲𝘃𝗲𝗻𝘁, the latter a 𝗽𝗿𝗼𝗰𝗲𝘀𝘀.
In our Protestant faith, justification is a 𝗹𝗲𝗴𝗮𝗹 or 𝗳𝗼𝗿𝗲𝗻𝘀𝗶𝗰 𝗱𝗲𝗰𝗹𝗮𝗿𝗮𝘁𝗶𝗼𝗻. It is the instantaneous legal act of God, in which He forgives our sins and declares us to be righteous in His sight, on account of Jesus’ atoning death and resurrection. This is the event of conversion when a sinner puts his faith in Christ and His finished work on the cross. Justification is a legal declaration, not a moral transformation.
Sanctification is God’s 𝘁𝗿𝗮𝗻𝘀𝗳𝗼𝗿𝗺𝗮𝘁𝗶𝗼𝗻 of a believer’s whole being, through the work of the Holy Spirit. Every part of the person is changed – his thoughts, values, attitudes, affections, words, behaviour, and actions. The ultimate goal of the Holy Spirit (who dwells in us), is to transform the legally righteous convert into a morally virtuous person.
Sanctification is a lifelong process through which we die daily to sin and learn to live more and more for righteousness. This is how we grow in Christlikeness or holiness. To be holy is to be Christlike, and the Protestants call this “growing in grace” (2 Pet 3:18).