The lifelong process by which the justified believer is gradually conformed to the image of Christ. Distinguished from positional sanctification (the once-for-all setting-apart at conversion, 1 Cor 6:11) and from final sanctification (the perfection at glorification, 1 John 3:2). Progressive sanctification works by the Spirit applying the word to specific sin patterns over time, with the believer's deliberate participation: work out your own salvation with fear and trembling. For it is God which worketh in you both to will and to do of his good pleasure (Phil 2:12-13). The paradox is real: God works, AND the believer works; the works are not in competition. Sanctification is not earned (it is grace) but it is also not passive (the believer is commanded to pursue it). Slow, real, often invisible from the inside, the mirror at the end of the process is Christ Himself.