To sanctify is to set apart. In biblical usage the word carries the sense of consecration—removing something from ordinary use and dedicating it to God. Temples, altars, priests, and the Sabbath were all sanctified. The underlying idea is holiness: what belongs to God is not to be treated as common.

The New Testament applies the same language to people. Believers are described as already sanctified by the work of Christ and at the same time called to progressive sanctification in daily life. The tension is deliberate. Justification declares a person righteous; sanctification is the lifelong process of becoming what that declaration says they are. The Holy Spirit is the agent; the means include Scripture, prayer, the sacraments, and the mutual encouragement of the community.

Different traditions map the process differently. Some expect a distinct second experience of entire sanctification; others see a gradual growth in grace marked by increasing conformity to Christ. All agree that the goal is not moral self-improvement for its own sake but a life that reflects the character of the God who is holy.

When an object or a person is sanctified, the ordinary is claimed for a higher purpose. The word still carries that charge.