Not To Be Confused With
Justification is a once-for-all declaration; sanctification is an ongoing process. Some traditions fold them closer together; the Reformation insists on distinguishing standing from growth.
From the same root as “holy/saint.” The Spirit conforms the believer to Christ (2 Cor 3:18); the human side is real effort (“work out your salvation,” Phil 2:12) — yet “it is God who works in you.” Traditions differ over perfection, means, and the role of the sacraments.