That is the meaning of sanctify - to set apart from sin.
To sanctify is to set apart for holy use, like gold vessels in the temple for God’s glory, not common clay (2 Tim. 2:20-21).
Through union with Christ, believers are positionally sanctified—declared holy by His imputed righteousness (1 Cor. 1:30; Heb. 10:10), which is a gift of grace.
We’re also called to progressively grow in practical holiness (1 Pet. 1:15-16), which is enabled by the Spirit (Phil. 2:12-13) and is likewise, still positional.
Sanctification, positional and progressive, flows from Christ’s work, setting us apart for God’s purposes (Rom. 6:22). While it involves separation from sin, God can use anyone, like the thief on the cross, whose holiness is Christ’s alone until our ultimate glorification.
I’d nuance your definition slightly: sanctification isn’t primarily about sinlessness but being usable for God’s will and glory. He both begins and completes this work (Phil. 1:6).
Yeah I do, Jude 1:1 makes it clear
Jude 1:1 clearly teaches that believers are simultaneously called, beloved in God, and kept for Christ—distinct yet inseparable aspects of our standing, not a progression. The moment we are justified by faith, we are positionally in Christ, His righteousness imputed to us (Rom. 4:24; 2 Cor. 5:21).
God calls us out of the world into Christ (John 15:19), and while progressive sanctification may lead to greater tasks (Luke 16:10—“Whoever is faithful in little is faithful in much”), the apostles primarily speak of our calling as our initial salvation in Christ.