sanctificatio

Sanctificatio is the Latin term for sanctification, the process by which a person or thing is made holy or declared holy. In Christian theology, the concept encompasses both a status of being holy and the ongoing transformation into holiness. The noun derives from sanctus 'holy' and facere 'to make'.

In Roman Catholicism, sanctification is the work of God by which grace develops virtue and holiness within the believer. It begins at baptism and is nourished through the life of the Church—especially the sacraments, Scripture, prayer, and the practice of virtues. Sanctifying grace is considered a real, animating presence of the Holy Spirit that enables the believer to live in accordance with God's will. While justification by faith points to a forensic acquittal, sanctification describes the ongoing growth in holiness; cooperation with grace is emphasized, but grace remains fundamentally a divine gift.

Many Protestant traditions distinguish between justification and sanctification. Sanctification is the Holy Spirit's work in the believer to impart righteousness and moral transformation, often described as progressive sanctification. It is experienced throughout the Christian life and is inseparable from faith, though not meritorious in itself; it evidences a changed life rather than earning salvation.

In Eastern Orthodoxy, sanctification is closely tied to theosis, or deification—the process of becoming united with God in holiness through prayer, ascetic practice, the sacraments, and participation in the Church's life.

The term appears in the Bible in Greek as hagiasmos and related forms, and in Latin as sanctificatio; the concept denotes holiness as a gift and as ethical transformation produced by grace.

Sanctification is often linked to universal calls to holiness and to the role of sacraments, prayer, and ethical living across Christian traditions.