Justification means our declared righteousness before God, made possible by Christ’s death and resurrection for us. Sanctification means our gradual, growing righteousness, made possible by the Spirit’s work in us.
1 PETER 1:1–2
To those who are elect exiles … according to the foreknowledge of God the Father, in the sanctification of the Spirit, for obedience to Jesus Christ and for sprinkling with his blood: May grace and peace be multiplied to you.
Collin Hansen, ed., The New City Catechism Devotional: God’s Truth for Our Hearts and Minds (Wheaton, IL: Crossway, 2017), 141.