What does it mean to be sanctified by God?

Sanctification is a vital aspect of the believer's identity, referring to the process by which God sets apart individuals for His own purposes. As stated in Jude 1, believers are 'sanctified by God the Father.' This past tense indicates that their sanctification is a completed act whereby they are chosen and made holy through Christ's sacrificial work. Being preserved in Christ signifies that believers are kept secure in their salvation, not relying on their efforts but wholly on God's faithfulness. This doctrine fosters assurance among believers, reinforcing their position in Christ and their identity as those sanctified unto good works.