How do we know our sanctification is true?

The assurance of our sanctification is rooted in our belief in the gospel of Jesus Christ. In 1 Corinthians 1:5-7, Paul states that the testimony of Christ is confirmed in those who are enriched by the gospel. This enrichment comprises recognizing and affirming the truth of Christ’s work, which leads to the assurance that we are truly sanctified. It is the Holy Spirit’s witness in our hearts that confirms our status as God’s people and the transformative work taking place within us, ensuring we are equipped and preserved by God's grace until the end.