Sanctification is the Bible’s language for becoming holy — being set apart for God and, over time, being made to resemble him. The Greek New Testament term, hagiasmos, is built on the word for “holy,” and in Christian theology it names the work by which the Holy Spirit conforms believers to the likeness of Christ.
The root idea is old. Already in Leviticus 20:8 God calls himself the LORD who sanctifies his people — who sets them apart. The word keeps both senses throughout: a status (set apart as holy) and a process (being made holy).
What the churches have taught
How sanctification relates to justification — being declared right with God — runs along one of the dividing lines of the Reformation.
In Protestant theology the two are carefully distinguished: justification is a one-time, forensic declaration, in which God pronounces the sinner righteous, while sanctification is the gradual transformation of character and conduct that unfolds over the believer’s life. Catholic and Orthodox traditions understand the two as more organically united — dimensions of a single saving process rather than separate, sequential events.
On either account, the destination is the same: a life increasingly shaped to the holiness of the God who called it.
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How this is made · A Fortt Media project, created & edited by Jon Fortt. Grounded in a curated Scripture database and carefully drafted and audited with the help of AI — described plainly, and written to assume no particular denomination or doctrine. Read the full approach → · Report a correction →
