How do we know that being sanctified in Christ is true?

Sanctification means being set apart for God's purposes and is a critical aspect of the believer's identity in Christ. In 1 Corinthians 1:2, Paul addresses the church as those who are sanctified in Christ Jesus, emphasizing that true holiness does not come from personal merit but through Christ's work on our behalf. Because believers are in Christ, they are declared holy before God, an act that is both immediate and complete upon their union with Christ. This truth is foundational in understanding our status before God.